His symptoms do not indicate a STD. He could have gotten gonorrhea, NGU or syphilis from his oral sex exposure. But all STD's are difficult to transmit via oral sex and without symptoms (burning while urinating, discharge and/or a sore) I would not worry too much about a STD.
But if he got oral sex, who's to say he didn't get more? Or who's to say he has not done more in the past.
It is always a good idea to test to find out your status.
.. Unprotected sex = risk for ALL STDs and HIV. Even though it's reported that GentiaL herpes increase one's risk of HIV , he wouldn't have contracted Hiv from oral sex...