Posible STD

Patient: Hello, about 3 weeks ago I started experiencing a painful burning feeling when urinating. I was seen by an ER doctor who took a urine sample and said i had a bladder infection, I was given an antibiotic and a prescription for Pyridium to stop the pain. Now the pain is gone but my penis and testicles itch alot and if I itch them it burns. As well, I have noticed over the past two days that my semem is yellow. I was wondering if these can be after affects of a bladder infection or is it possible that I have contracted a STD?