What Causes Bruise Like Pain On Posterior Thigh?

Hi, I have a little bruise-like pain on posterior thigh of my left leg. The pain is very little and only noticable when I sit or press the spot with my fingers. When I walk I feel no pain and there is no real bruise or any sign on my skin at the area.But I have it 2 weeks I think and it doesn't leave. Any opinion?