During a workout and doing leg curls, while lying in face down position. I felt a strain in back of the knee at the curl point. I thought it was a muscle strain, but it seems to have blown out a small vein that has continued to be discolored like a bruise and slightly enlarged for over two weeks. It still seems strained and slightly uncomfortable. Main concern is the occasional bubbling sensation in the calf area below. Seemingly related not to muscle spasm but blood flow into the calf. However, no swelling in the lower ankle or calf. No discoloration, no loss of mobility and no loss of sensation. I do not take any medications and am in good health