Hi, I am a married male aged 35 years. I have been treated with mouth cancer 2 years back with surgery and radiotherapy with concurrent chemotherapy. Last cycle was in August 2014. I have a problem now in which when my penis get erected then the skin gathers just below the top of my penis, like a ring of skin. Because of this I feel pain while having sex with my wife during inserting my penis into the vagina. I have observed this issue only for last 1 year or so. Can you please help me to know what is the problem and how can it be treated?