ok well i am a 14 year old boy and we got a jucuzzi. So all boys try to do stuff to make themselves feel good right. Well i was 13 and i was in the jucuzzi. And when i moved over my penis got in front of the air jet and it felt really good. So i kept doing it i didn't think anything wrong with it. But after doing it regularly everytime i got in the jucuzzi. After a while i noticed a black mark right on the side of the part where urine comes out. I havent got in the jucuzzi for quite a a while now but i do masturbate a lot. And the black mark hasnt gone away. Will this thing go away or do i got some sort of disease. PLEASE TELL ME IM SCARED :(

PS. SHOULD I STOP MASTURBATING SO MUCH. IS THAT THE PROBLEM???