For the last few months ive had a recurring pain in the back of my knee, not the kneecap but the back of the leg where it bends. Everytime I think its better I make it happen again by stretching(sideways splits) or kicking high. It kind of feels like the hamstring but hamstring stretches have no effect on it. I mentioned this to my GP but he wasnt bothered as it doesnt effect my walking or going up stairs. Anyone have any idea what this could be and or anything I can do about it? Its starting to annoy me now as its my good head kicking leg.