What Causes Pain At The Tip Of The Penis After Intercourse?

i have got married last year, recently from past 2-3 months i get pain on the tip of the penis. initially when i used to have sex with my wife it used to be painful and then after intercourse i get pain and even cuts on the skin covering the penis. later this cuts have gone. but now when i retract the skin covering the penis its pain and i found white patches on the tip of penis. is it serious should i consult a dermatologist