A week ago I strained my hamstring and MCL in martial arts class due to a high kick (muscles were very tight at time). 3 days later I noticed some small bruising and later that same night I aggraveted the injury to the hamstring. For the most part, my leg feels much better and the swelling has subsided. I'm gaining the flexibility back but there is a very large bruise which is now covering my entire hamstring and back of knee and it has progressively spread over the last 4 days. Is this normal or should I be concerned ? There is a bit of discomfort but it's not very painful at all.