A lot of things could cause this including but not limited to; a cyst which is simply a sac filled with fluid that poses no risk to health whatsoever, especially when it’s benign so don’t worry too much about it or even something called varicocele where there’s swelling in one or more veins within the scrotum usually above the testicle on same side but less likely but still possible is cancer so I would advise getting checked by a urologist just in case.

If you have pain and discharge from your penis, that might be due to an infection. Sometimes those infections (like urinary tract infections or prostatitis) don’t show up on STD tests. It’s important to have a full check with a urologist and maybe some other tests to work out what’s going on. Once we know what’s wrong some treatments work well.