It sounds like an infection or inflammation in your prostate. This could be caused by the chlamydia, but there is at least an equal chance or a greater chance that it's caused by something else, if this is what you have. You may also have an infection in your urethra, which could be caused from normal mouth bacteria, if you've received oral sex since the encounter 7 months ago. It could also be a urinary tract infection.
If you haven't yet, you need to see a doctor to find out what this is. You'll likely have to pee in a cup, and perhaps have a prostate exam.
A note - It's quite possible the girl didn't even know that she had chlamydia, and I hope you did the adult thing and let her know that she needs treatment. Most women don't get symptoms, and an untreated infection can lead to serious consequences.
Any time you have unprotected sex, you take a risk. She is not the only one at fault here.