Suggest Treatment For Deep Purplish Large Lump In The Leg

My upper leg started to swell and I noticed a large lump on the back part of my upper leg. I thought it was a charlie horse but it wasn't, a few days after the initial symptoms my entire upper leg on the back got a real deep purpleish red color and was very warm to the touch. It hurts continuously. I am wondering if it is a blood clot.