I had a wierd back thing last week. I was doing just grip fighting with out top guy. It use to be not too bad because he was 2 weight classes below me so it was harde for him to do stuff and he was not nearly as strong. However, starting last summer he started lifting hard and now I only have about 15 lbs of fat on him. He was jerking me around, doing a lot of popping stuff. We stopped that after about 45 minutes of going pretty hard non stop and he started working is drop knee seio. My back was already sore, but after about 30-40 throws stood up and my left leg kept shaking and my back was killing me. Seemed just like a tensed muscle or something...any ideas?