Hi Doctor, My penis stretches upto 4 inch on erection . The foreskin is not retracted. I have to slide it back manually. The problem I have is, I am unable to penetrate. It becomes erect after foreplay. As I try to enter, where I feel as if I am hitting a wall, it loses erection. I have taken Megalis, where I get good erection, but still feel, it is hard to penetrate.