There are a lot of muscles that attach there. It's the "bump" on your bone right below your knee called the tibial tuberosity and it can be quite painful if the tendons that attach get inflammed. If you have been running on concrete a lot and especially if you have been running downhill, it could be a problem with your quads causing the pain. Oftentimes a problem with one part of the body will be felt somewhere seemingly unrelated. All of the muscles of your quadriceps attach at your tibial tuberosity and if they are really tight from bracing against impact, they can pull at the tendon that attaches them to your lower leg causing inflammation and pain. You need to be very careful because tendon attachment sites are a prime area for stress fractures. If the pain gets worse with ice and not better, take time off immediately and get a bone scan.
Also, some inner thigh muscles attach more medially to your upper shin area, so if the pain is slightly inside, your problem is probably with your adductors. Surprisingly, your hamstrings could also be the problem if you are experiencing pain more to the inner side of the upper part of your shin bone. The problem is most likely not at all due to your lower leg muscles (since they don't attach at your tibial tuberosity) but due to tightness and/or weakness of your thigh muscles. Try massaging your quads (especially right above your knee) and have someone massage your hamstrings. The stick (a massager thingy) works great for this kind of thing. Ice the area before and after you run (give it a little time to thaw out before you head out the door) and take anti-inflammatories like ibuprofen for awhile. Until you have ruled out a stress fracture it is probably a good idea to cross train or take time off. Don't bike because biking uses your thigh muscles heavily. Instead water run or use an elliptical at a low resistance.
Good luck and I hope your pain goes away soon!