tibialis posterior tendon?

Hi, I'm a runner currently suffering from pain in the inside of my ankle/calf which runs to behind the ankle bone. It has been very sore to touch and I've been unable to run on it for about six weeks. It is sorest when walking down stairs. I'm also having pain up the back of the calf. I have quite a big scar in this area (caused by removal of a melanoma about three years ago) but this hasn't caused me problems previously (though I have noticed more stiffness in this calf than the other).
If it is the above, is there anything I can do for it apart from rest, AIs and stretches? Should I be keeping it mobilised or strapped? And how long might it be before I can start running again.....???? Very depressed!