I'm sorry to hear that you are still dealing with this issue from 3 months ago. A sprain, as you likely know, is an injury to the ligaments that surround and stabilize a joint, commonly the ankle, although all the other joints can be sprained as well.
Sprains can take a really long time to heal. This is in part because ongoing use of the joint may slow healing. It is also due to the fact that blood supply to ligaments is pretty low, which further delays healing. All in all, it is not at all uncommon still to have symptoms several months out from a bad sprain.
That being said, I would definitely recommend medical followup at this point. Your doctors
">primary care doctor, for example, can look at the the ankle to see if there is any evidence of a more severe or persistent injury, such as a torn ligament (rather than just a sprain). Sometimes, it may be necessary to be referred to a specialist, such as an orthopedic doctor, because severe sprains or ligament tears that are not healing properly will occasionally require surgery
. At this point, if your symptoms are still severe, your doctors may want an MRI to get a better look at what is going on inside the ankle.