I had a Kenalog injection for an allergic reaction over 7 months ...

I had a Kenalog injection for an allergic reaction over 7 months ago which worked like a miracle. I couple of weeks ago I noticed a large indentation in my lower hip at the injection site. It's like the surrounding fatty tissue is gone so now I have a big hole in my butt. I talked to my doctor if this could be from the Kenalog shot and she agreed it may very well be, and that I should have known the side effects when I signed the permission sheet before they administered the shot to me. I don't know what to do at this point but I am very upset and wish to seek legal action. All I want is to get it fixed. I am very self-conscious about the clothing I wear and every time I feel it, it's like a deformity. Anyone who can offer me info on taking legal action I would really appreciate it. Thanks!!