I've had a an injury at my left buttock. It went like this: there was a heavy object falling down and I suddenly caught it with a slight twist in my body... It resulted in a pain in my lower back area, and not being able to completely stand up... The pain area receaded gradually after few days. A few weeks later, now, there is still some pain in my upper left buttock, plus my left thigh area gets tired faster than my right thigh when I do sqats, and the after workout "pain" lasts longer too...