What Causes Cracking On The Skin Of My Penis After Intercourse?

Skin on my pennis always cracking..when I have intercourse with my wife after that it will stay for 3-4 days atleast I am using coconut oil as remedy it is helping much its a couple of months. occurs every week and I have give a gap in my sexual life. it became a problem in my personal family life. the cracks always troubling in even while i go for urine as my pennis shrinks very small when no erections. could you explain what should I do to resolve this problem. I am 40 yr old, I don't have any other sexual relations.. I have only habit of taking beer.