hai doctor

I am a male 42 years old and have 2 children. I have sexual problem, recently I read one case about my pennis. While errection the down portion skin is fixed with penning. its not going to down and roll out. I am getting pain while intercourse with my wife, feeling very badly, can`t enjoy the sex. Also now a days very week, not getting much stamina to get sex. pls replay to me urgently, also tell me which doctor can help me.