Any help what this can be: I have pain in my left buttock where it meets the top of my leg. It almost feels within the joint. I first noticed it when sprinting and it has got progressively worse. It doesn’t hurt when doing hamstring curls/lunges etc in the gym but is very painful when sprinting. It aches when I sit down and the stretch that I find very difficult and painful is when I place my leg out in front of me at right angles, bend the knee and then then lean forwards. I’m usually very good at diagnosing what my body is telling me but this is getting very frustrating and painful. I have no back pain nor pain down the leg and have been taking anti-inflammatorys but they do not seem to be helping. Any advice would be greatly appreciated.