had this problem
Great info in the post above....But it might be where you are running as well.
Near my house I have a park, with a lake and a track around it, nice flat area, I can run 2 miles, no pain.
now my street is a 1/4 long, so I can use it as a track, but my street is very hilly and has sidewalks that are on a angle, going sideways, that is not so good.
Anyway, I ran a few times around my street, same distance...started getting shin splints, I stopped, I returned tot he lake area...no problems.
The street and the hills plus angle sidewalks, was just bad for my legs and it is not worth the injury, so I go to the lake and been good since.
Check the area you are running and also follow the advice above, I am big into stretching, it is key.