Anterior shin splints do not take as much time to heal, so I hope that's what it is. These are on the outside of your shins and from what I've read, are the results of a small muscle growing faster than the sheeth of that muscle... so the outside sheeth is stretched. HOWEVER, this pain should generally go away within three or four days of resting. Mine sometimes went away after a single day. This can be caused (as the prior poster stated) by uphills, concrete running when one is not accustom to it, longer distances than one is accustom to, etc.

The other kind of shin splints are felt in the inside of the leg and are a bit more severe. As I understand it, the attachment to the bone is beginning to separate and is very irritated. It will take weeks to grow strong connections. I've not had this for two decades, so I can't recall it in as much detail. I don't know all the causes... mine was caused by poor shoes and pounding on hard surfaces when I was not accustom to running at all.

I sure wish you well.

Mark

I still worry about how fast you built up your miles though. While its great that you're in good enough shape to do that kind of milage, your joints, bones and muscles just aren't used to that kind of pounding yet. I know how tempting it is to bump up your milage more than 10% every week. There's nothing worse than running 6 miles and stopping when you feel like you could easily run a few more...except for maybe losing a few months of running due to injury.