Itching In Penis, Burning Sensation When Urinating, Small Swollen , Painful Black Dot At The Tip Of Penis. Diagnosed Bladder Infection. No Relief From Antibiotics. Advice

Hi, it started a few weeks ago when i felt a mild burning sensation when peeing. I went to the doctor and he prescribed antibiotics and his diagnose was blatter infection. After taking the antibiotics i felt better but suddenly a few days later it started all over again with strong itching sensation in my penis, mostly at the tip. Few days later the itching had evolved to pain, especially at the tip of the penis. Tests for chlamydia came negative and now i have noticed a small black dot which is a tiny bit swolken at the tip of my penis which hurts, especially when peeing. I don't know what to do next... My doctor said the black spot is nothing to worry about but the source of the pain is situated at the spot. Any advice is appreciated