Hi There

I have a sore penis muslce, like down the bottom only when its hard. When its soft its completely normal and no pain what so ever, only when its hard and I move it to the right it hurts a bit like a pulled muscle. Im not sure if I have hurt it through sex 4 weeks ago or doing it myself, its been like this for about 5-6 days when I woke up the other morning and was laying on it and noticed it. What do you think it could be?

Troy