First, regarding concrete, you are better off on a  flat  concrete surface, than on the slanted side of a road. Concrete is   indeed hard, but black top is not much softer. The road surfaces, often   slanted for better drainage, can create new injuries quickly. Better   still for recovery, would be to run on the kind of soft, well maintained   grass one might find on a golf course. Just expect to get chased off  if  that's what you do!

Some will recommend a treadmill,   but that depends on the quality of construction. If you do train   indoors, turn the incline off. It is likely to hurt more than help. All   this is if you continue to run, but I think it's time for a break to   rest and analyze what's wrong. You will lose some fitness, but stand to   lose much more by running through an injury. There is always pool   running and ellipticals for safer rehab with minimum impact.

I  remember wearing a knee brace in the early years of  my running, and an  ankle brace as well - even through races (not  recommended). I've worn  tape and arch supports, too. These devices  certainly will boost your  confidence, but remember they are props that  won't replace healing  what's hurt. The hurt comes, unfortunately from  overuse - what we call  "too much, too soon." Your body hasn't yet  adapted to the rigors of  your training, and your patience needs to match  that rate of  adaptation.

Of knee braces, I have read  they may help to  stabilize a knee that is structurally loose, but the  long-term effect  of running with them can include problems associated  with restricted  circulation. While this can have a numbing effect,  maximum circulation  will do more for your injuries over time. If your  knee is unstable, it  is more helpful to strengthen the muscles that act  on the knee, getting  your support from inside the body rather than from  without. I am a fan  of compression shorts and tops for better cooling,  aerodynamics, and  less chafing. Running/competing with therapeutic  compression gear,  though a current fad, has short term gains at the risk  of long-term  losses. If you feel the need for this stuff, there are  other strategies  that wil benefit you more.

Again,  circulation is key;  it's what heals you. We often hear about icing and  stretching, but both  are halves of a better whole. Ice alone is for  acute injuries, while  alternating cold and heat does more to stimulate  circulation in working  muscles. Stretching can invigorate healthy muscle  tissue, but a muscle  that is tight or in spasm can be easily damaged  further by stretching.  Massage, including self-massage, followed by  light stretching, is a  more professional solution that delivers better  (and safer) results.

Once  you are on the mend and  loosened up, it's time to strengthen your  quads, calves, hips, and core  muscles. Strong, healthy quads and calves  absorb more shock and smooth  your stride. The quads alone guide your  kneecap and stabilize your knee  so wear and tear within is less likely.  Increase your mileage only when  these are strong enough to protect  your entire run. Running tired on  wooden quads will lead to damaged  knees. You can relax the quads by  kneading them between thumbs, palms,  and forefingers. Straighten the leg into a relaxed position first.

Likewise,  tired calf muscles, some of which cross the  back of the knee from  lower to upper leg, can produce pain within the  knee. Ditto when they  are overworked and too tight. Always target your  therapy in both  directions - to strengthen and relax. One without the  other is asking  for trouble.You can gradually relax many of your calf  muscles by  sliding them down the opposite knee when seated, even at  work. Let  people stare.. you're an athlete!

The hips and core  muscles are what provide the  stability to your stride, and reduce  lateral and twisting stress on your  knees. Once again, you can't overdo  it. Too much stiffness in your core  (back, abdominals) and hips will  result in back pain and muscular  compensation below. Tight back  muscles, and upper glute muscles around  the hip, are easily loosened by  laying them on a tennis ball before bed. Abdominals are best approached  by hand.

Some knee pains result from the area known as  the  Ilio-Tibial Band (ITB) on the lateral quad. While some pain can be   traced to the Band, the quad is highly vulnerable to running. Many   athletes have learned to do regular maintenance on this area with a foam   roller to insure that knots of tight tissue to not develop in these   structures. If that's what you have time for, it's better than nothing,   but I've found ways of using my hands and available soft furniture to   accomplish the same circulatory benefits, almost anywhere, any time.

All  of this strength and speed sits on the all-important platform of your  feet. While shoes are for most, an important part of the picture, the  type of foot you have must be matched not only by the shoe you wear, but  for many, by modifications to your shoes to account for extreme  variations in foot structure that are not addressed by the shoe  manufacturers. Many orthotics have you running on your arches - not the  best thing for an athlete. A solid knee requires a smooth, efficient,  and natural footstrike. This is a complicated issue that warrants further discussion if you need it.

I   trained for my first Half mostly on concrete, and I recall how painful   it was. As I got faster and more vigilant, I found ways to mix my   surfaces with better results. In my opinion, the best places to train   for racing are parks that are closed to thru-traffic. This most closely   approximates the average racing environment of full road use, flatter   surfaces, and less concrete.

However, not so fast -  try some of the suggestions above to take care  of the tension on your  knee, and when it feels better, you can work on a  moderate course of  strengthening exercises. Then (within a few weeks),  back-track your  training somewhat until you are strong enough to up  your mileage.  Meanwhile you have productive ways to spend your down  time. Be patient with your body, or you might spend six months down like  I did!