question: I was white water canoeing when we flipped and I took a very hard hit from a rock in my upper right buttock. The sight has become very swollen and also become very hard. I m sure it s just a bruise but I want to make sure. I had stints put in in January so I m also on a 75 mg of plavix daily. Wondering if this will have any affect. Wondering if I need to go to the ER or not.