Congrats on your 5K completion! 

Be careful about pushing it too hard - sit out for a week or two.  If you have true PF, you'll need to rest for at least one month (maybe two) and mix in a regular dose of anti-inflamatories, stretching and perhaps even a night splint.  Search PF for the appropriate stretches - the runners stretch is a good one and targeting your achillies will help stretch that tendon that runs under your heal and across the bottom of your foot.  My foot doc told me to, along with my normal rehab, start my day off by drawing the alphabet with my injured foot before I get out of bed - it'll help get the blood flowing and stretch everything before your feet hit the floor for the first time of the day.

I injured myself training for a 13.1 back in Feb 09 and am just now healing from an extended case of shin splints and plantar fasciitis.  Not withstanding the bonehead training schedule I was following, I ended up trying to get in a couple of runs after my injury and ended up further injuring myself.  It's late October and had I stopped running completely and healed properly I probably would have been back running some time in June or July...  Still not running - talk about losing the gains I made...

In short, if you are feeling pain take it easy.  Give yourself a break, hit the stationary bike or the elliptical.  You'll lose more of the conditioning you've gained thus far if you push yourself too hard than if you just take it easy for a week or two (or whatever your foot doc suggests).