What Could Patches On Penis Shaft With Tight Foreskin Suggest?

i have a slight problem, the top of my penis (head) is a different colour to my shaft. My whole life i have had a tight foreskin but have recently cured it myself and can only just pull back behind the head when erect. The shaft is skin colour and the top of my penis is a very dark colour, more of a reddish purple. It functions properly but feels saw when rubbed, however not so much if hardly when its wet. After masterbation the head seams to have small patches of red areas round it. Please tell me whats wrong else i cant be sexually active until i know. Also the head is still sensitive.