Not sure what is the cause of this

I had unprotected sex with a random girl that i met. About 2 weeks later i had itching in my genital area, and the doctor tested me for chlymidia and gonorrhea and they both came back negative. She gave me some cream to put on, and eventually the itching went away. About a month and a half later i started experiencing lower abdominal/pelvic pain and slight irritation in my penis. I went back to the doctor and he did a urine analysis and a blood test and nothing came up. He also performed a rectal exam and nothing came up. Recently a small bluish mark on my penis, around the glans showed up. I don't have any sores, and i don't feel any major pain, but I have continued to feel aching in my lower abdominal/pelvic area and very slight irritation on my penis. I don't know what this could be or what tests I should have done next.