Suggest Treatment For Bruising And Discoloration On Thigh

I have had large areas of bruising and discoloration on the inside and back of my upper right thigh. It's been there for 8 months. Four doctors have looked at it and don't know what it is. I was examined to make sure it wasn't a blood clot and those tests were good. The skin is really tough (almost like thickened) in one spot.