Thanks Life360 for the info/advice.
Hi and welcome. Since the pain started with the Gono infection its most likely connected to that incident. With Gono the urethra has become like an open wound and part of the wound could be near your penis tip. Also you most likely have been over checking this area out of anxiety which is quite common and caused the irritation your self. Also if the doctor did a swab it could have added to the already irritatated area.
See how it goes over the few days. You also should follow up with your doctor for a re-test to make sure its gone before becoming intimate again.
Since you got this you were also at risk for a few other things and should follow up with a full panel testing, including herpes, syphilis and trich just to rule them out.