I Developed Discoloration In My Right Thigh. About 10 Days

I developed discoloration in my right thigh. About 10 days ago I slipped on the snow & hit my butt on the right side but otherwise was OK. I flew from Portland to San Francisco to San Antonio on Saturday. Besides the discoloration I noticed my thigh has continued to swell. There's really not pain. I'm in a small town in Texas until Saturday & I'm not sure what, if anything to do.
I'm 66 years years old with a bunch or preexisting conditions.