Hi, my friend had oral sex(only oral) with a hostess in a nightclub in toyko and returned with white discharge from his penis and pain when urinating. He thought it could be an STD but after a comprehensive test, he was cleared of everything except Citrobacter diversus and UTI . He just finished a 7 day treatment of antibiotics and was good for a week. However these few days the white discharge from his penis came back. What is going on?