What Causes Red Blotches On The Penis?

i notice that the head of my penis becomes somewhat covered in red blotches. the head is not fully covered but has been spreading. Today after masturbating the area was very dry and looked like it was covered in dead skin. I got a wet cloth and wiped off the white making it red again, however a tiny cut appeared which gave cause for alarm. The area doesn't hurt or itch, it just looks unpleasant, like a rash that won't go away. I've only had sex with one woman who tested clean of any STD's. We had chlamydia for a little while without knowing it, but got tested and cleared of it a while ago. What could this be?