How can i make my my situation with my penis better?

since i was young i either master-bated or had sex several times a week. I am 20 now. 2 yrs ago i was having sex with my ex gf and noticed i wasn't as erect as normal and my penis was noticeably red. I put it off hoping to get better, but the relief never came. As time progressed i could get hard again but it felt like my penis was numb and my boners were no where near as erect. As time progressed further to my current state..... I am now in a lot of pain when i use my penis and even when i dont. its not severe but i want things back to normal, PLEASE HELP...i went to the doctors a few times and he kinda blew it off. i had an std test done and most of the tests were negative but the lab screwed up and couldnt get the results for the other tests. MY OTHER SYMPTOMS( my penis is hot which makes me think infection. i have not been able to last as long in bed because of the sensativity of my penis, sometimes it hurts to even get a handjob. there is bruising around the head , to me it seems i have more veins running to the head as well. when i *** it doesnt feel the same like a stinging pain. i have noticed no leakage in the period of time tho. i really need help pleasse