Penis Head Disease?

Hello everyone! I am a 20 year old virgin and have been masturbating ever since i have been 11 years old. I used to be really turned on and masturbate a lot. and ive tried many methods of pleasuring myself. but not disgusting methods that are shocking. By the age of 14 I noticed that I have an abnormal penis head compared to all the penis heads I have seen in porn videos/pictures and have been too afraid to talk to anyone about it until now. The shape and all that seems to be fine. The problem is my penis head isnt smooth. well the rims of my penis head is normal but farther away from the edge of the heads are not smooth. how can i say this.... ? umm.... theres little crevices throughout the head of my penis. it doesnt hurt or anything. but its rough when i rub against it when i masturbate. and it was the main reason why I have been avoiding sexual activity and I'm afraid it will continue to be that way unless I can solve my problem. I'm not entirely sure how my penis head ended up that way. I tried searching for penis deseases on the internet but couldnt find anything that matched the problem that i have. Can anyone please help me? :$ :'(