Pain & inflammation on right testicle. pus cells in semen and urine analysis. e.coli was found in urine culture. why and what causes this? is it stds?

Epididymitis: You need to see a urologist and have this condition assessed thoroughly. As already indicted, the e. Coli may or may not be of significance and you must place its isolation from the urine in the proper clinical context. Go and see someone soon. Unlikely to be std but if you have been exposed, go and get tested. Good luck and best wishes.