Medial Ankle Sprain/pain

Medial ankle sprains(assuming it was your deltoid ligament that was damaged - did you get a diagnosis?) can be a long time healing as one of the natural movements of the foo(pronation) will involve a certain amount of inherant tension in the deltoid ligaments. The tissues will heal but only if the aggravating force is removed/reduced to within the limits of stress for that particlar structure.

I am assuming it is a ligament as you have said sprain. If you haven't had it diagnosed it could be muscular

If it does not settle over the next little while, I would be inclinied to see a musculo skeletal podiatrist who may be able to diagnose whether it is muscular or liagamentous. Either way, they should be able offer some type of treatment which could be continued rest or perhaps ankle taping to reduce the stress on the injured structure and allow it to heal.

My point being that it could be one of several different problems and the only way of determining this is to see the right person.