Yep, I believe my pain resulted from intense stretching. Urologist told me I have Varicocele, so I’m not sure if my stretching just aggravated it or what. This often occurs in the left testicle where a vein in the testicle becomes dialated and can’t pump the blood back to the heart, so overheating of the testicle occurs and it produces pain (and may overheat sperm resulting in infirtility). Usually your testicle will hang lower and feel swollen a lot. It’s not serious though, but can be corrected with surgery if it is killing your sperm or the pain is too much to bear.
UltraSound also showed calcifications in my testicles. Going back soon to make sure these don’t evolve into something else.