Suggest Treatment For Ankle Sprain

I sprained my right ankle about 4 months ago...it's not a break. I went to the Rothman Institute in Philla and was given a shot of cortisone in my ankle. In the joint between the fibula and tibia where the front of my foot meets my leg and where the ankle bends. I have had rounds of PT and that didn't help. I had a cortisone shot yesterday and so far there is great improvement. I cannot fine the correct PI on here. I am an RN, but want to know when it peaks and the half life. I know I can have only 3 of these a year. Although it feels better today, the Doc. said I may only need just this one shot.....if the peak is only 8 hours, how can that be true? The half-life seems to be short too. I cannot find a PI on here. I have drug books and may resort to them, but really I was in such pain before the shot! It's ruined my golf game! Should I be using it full force or relax it? Anyway the shot was not IM, it was in the joint, and that name escapes me. Can I find the PI on line?? I should be able to, or I'll just look into my nursing drug books.