I had sex with my girlfriend and the next day found a tiny, barely visible red bump on the shaft of my penis.  The doctors told me it was folliculitus after all the std tests came back negative.  They even said it was ok to have sex with it, so I did and then it got irritated and after a few days it was like a small boil so i went back to the doctor and they cut it and drained out the puss. (this is by far the worst sh*t to happen to me by the way). he puts me on antibiotics and i look like I'm home free.  Then since it looks like the thing is practically gone and healed i get a blow job from my same clean girlfriend.  The next day its unhealed and it red again!  (I know I screwed up). so i went back to the doctor and he gave me more antibiotics and I've been taking those and the things looks like its healing but all of a sudden the last couple weeks as its healing my penis seems to have changed color and darker a little bit and just looks kinda different and swollen but not too painful and the head is really tender and the last few days if I get an erection the tube on the bottom shaft of my penis gets super huge inflated and swollen at the base and it looks more veiny than usual.  Theres just a little discomfort not much pain and the doctors weren't sure whats goin on.  Is there anyone that has any idea what could be happening?