Well, a few years ago I had a large lump appear on my knee, with lots of pain, about 5 days after my very first bike crash. The ortho doc thought for sure I needed surgery for some terrible thing, but an MRI showed it was just a bruise, so he drained the blood that had built up. It felt very much like you described. Beside the icing, elevating, and Advil, I did a lot of gentle quadricep stretches. At first, I couldn't bend the knee very much and walking up and down stairs was painful, but the stretching helped a lot. After about a week it was much better and I was riding again after 2 weeks. It might take longer to be in "running' shape, though.