Hi, my wife and I have recently had a resurgence in our sex life just this past month that has led to daily intercourse, many times through out the day. Just this past week, I've noticed the skin under my penis head, very red, very sensitive and what looks like some thin cuts around the circumference of my penis. During arousal and especially intercourse, I have felt pain. We've both been checked for STD's and have come back negative. What would can I do to avoid this problem.