Right testicle hurts at times tested negative for all std. what could it be?

This usually is not an STD symptom. Could be minor trauma, a prostate problem, or something else. Usually not serious, but see a doctor if it continues.

Pain in testicle without history of 'exposure' to STD did not warrant STD tests. There are many causes for testicular pain. Try wearing a scrotal support, use local hrat and otc Ibuprofen for a few days. If not better see a Urologist- for without exam no diagnosis can be made