What Causes Burning Sensation During Urination With Pain During Erection?

I have had sex for the first time 2 and a half months ago, we were both clean, and about 10 days ago i started to have burning in urination and my penis hurts when I get an erection. I have been to a doctor 2 days ago, she took a urine sample and said im perfectly fine, than did an examination and said i was fine there too, than took a blood sample and sent it to the lab. She claims everything seems fine, and she says it cant be a urinary track infection because i am circumsized. what is this?