Suggest Medication For Swelling Of Ankle After A Injury

I broke my ankle 4 months ago. I just started recently walking again and putting alot of pressure. It was fine for 2 weeks, but this past weekend my ankle swelled up tremendously. I ice it, and it goes down over night but it swells up again right away as soon as I start walking. My doc said I ahve a bone cyst, is this what it is? or do I have an infection?