Persistent ankle pain after a supposed sprain four months ago sounds very suspicious for more than a sprain. While it's difficult to be very specific without actually examining you or looking at x-rays, I suspect that you may have had either a very bad sprain (for example, a high ankle sprain) or a minor fracture
(break) of the ankle, both of which should be evaluated by an orthopaedic surgeon
. I'll go through each of these. In the case of the high ankle sprain, this represents an injury
to the ligament that connects your two shin bones (the tibia and the fibula) directly above your ankle joint. While it is normal to have a little bit of motion between these two bones, a sprain of the interconnecting ligament would result in too much motion, and this persistent motion would cause pain. High ankle sprains are a serious injury, and usually require surgery in the form of a screw or tight rope that spans the two bones, essentially serving the function of the injured ligament. In the case of a minor fracture (break) of one of the bones making up your ankle joint, not all broken ankles need to be fixed surgically. Non-displaced fractures (i.e. a break that has not moved or displaced) can be treated by casting depending on the pattern or break, but the key here is that even these most minor of fractures should be protected by cast and non-weight bearing. If this happened to you, I suspect that you putting weight on it either prevented it from healing or from healing correctly. If the break did not heal correctly, this can lead to arthritis of the ankle joint, which can produce pain on the "inside of the ankle". Again, please seek evaluation by an orthopaedic surgeon.