My first response is to not listen to rumors. Most of the time, they are vicious and not based in fact.
That said, it's good to get educated about these things.
Since you received, you are at risk for gonorrhea, syphilis, herpes type 1 and NGU.
Gonorrhea can live in the throat, and even if it's not a deep throat, which yours was, the act of performing oral on a man means that it would have gotten close to the throat anyway.
Syphilis and herpes type 1 (which would become genital herpes type 1 if you got it from oral sex) is far less likely if you didn't notice any sores, though still possible.
NGU is an infection in the urethra that can happen from normal mouth bacteria entering the urethra.
You can test for gonorrhea and NGU at 3-5 days, and syphilis at 90 days. Herpes is 4 months. If you don't get symptoms, I wouldn't worry too much about syphilis and herpes. You may already have hsv1 (think cold sores) and not know it, since 90% of those who have hsv1 never get cold sores. If you'd like to test to see if you have this, ask your doctor for a type specific IgG blood test. I don't see a big need to run out to get one, though. If you've ever had a cold sore, you can assume you have hsv1. If you do, you can't get reinfected with it again. I'd still avoid letting someone with an outbreak perform oral on me, but otherwise, you should be good.
Giving oral has similar risks, except you could get oral hsv2, though that's very rare.
Oh and ejaculating doesn't have a lot to do with it. You can still get these even if no one ejaculates. You ejaculating into someone's mouth doesn't increase your risk for anything, and perhaps increases your partner's risk for something a bit if you have gonorrhea.