Back/Hip Lump/Pain

I have had a lump on my lower right back just above the buttock, kind of on my hip that my doctor once told me was a "fat pad". I do not take any form of injections nor have I ever in the past. The last few months this area has become increasingly painful and hurts in the entire area. I'm not sure how to describe it but it hurts when I lay on my side, when I roll over, when I massage the area. This "fat pad" seems to be the cause of the pain. It hasn't gorwn or moved and I can sort of move it around but it is definitely attached and causes pain when I am sitting and when I get up to walk it is painful and I almost want to limp. It feels like it is attached to other things but I am at a loss as to what. Any suggestions would be greatly helpful as it is getting worse.