How do I treat a bad bruise on my thigh without ice?

This afternoonI was at Target and a jar of canola oil knocked over and spilled all over the floor. I fell on my side and there's a pretty nasty red and purple bruise there on my upper thigh. It's about four inches by two inches. I'm a bit concerned because it's swollen, although it only really hurts when I put pressure on it. I have a lot of muscle there because I do karate. I'm absolutely certain that none of my bones were harmed. I walked around a lot after I fell.

Problem: It's night and it's rather chilly, I would rather not use ice. What would you do?