Ligament injury in ankle from 3 months.

I fell 3 months ago while carrying a heavy bag and my ankle twisted and swelled and it painted a lot, considering it a simple sprain I just put a crepe bandage over it and took some rest but when it didn't got much better in 15 days I consulted a doctor he initially prescribed a medicine (I lost the prescription so can't mention the name) and rest. But again even after 1 month I was suffering through pain and had sweeling so the doctor said that it could be cured by applying plaster . So I had the plaster for 21 days with a multivitamin tablet prescribed by him but still even after 10 days of removing plaster it is as it is. So I would like a consultation as to what to do next so that I can cure it completely and permanently.