penis discoloration and pain.. please help dont know were to turn anymore!

new years of 2010 I had intercourse and the next day noticed a small cut on the glans (glands) of the penis but wasn't anything to bad and i just waited for it to go away. later i noticed my penis glans (glands) started to have a black spotted discoloration to them and it started to feel very painful at times. When i started to think that maybe it was just something that would go away i noticed around the edge of the glans (glands) little tiny bumps started to form and not long after that i started to have a burning and itching sensation in my anus that also still wont go away to this day.the head of my penis is becoming almost totally black and at time my glans (glands) will get really red and change sometimes to white discoloration spots where the black has'nt got to yet. another thing is that my penis head has formed these semi-deep crevices going from the edge of the glans (glands) to the meatus on the very tip and it covers the whole head except for the bottom right side of the glans (glands) which for some reason is even more black than the rest and the texture is almost that of touching saran wrap very very flat and smooth definitely not the texture of regular skin. when erect i notice that inside the crevices is what looks like to be dry flaky skin. i really need help with this problem because its emotionally killing me and physically hurting me im fixing to start medical school and hopefully can do something before school starts so i wont have this problem distracting me.   and yes ive been tested for stds and none have came up positive. i made sure i got tested for everything you can get tested for 3 different times since then (every few months). the black discoloration is spreading to the shaft of my penis and the glans (glands) are very uncomfortable at the times that they don't hurt. please help me