No, it isn't risk free, but it's a lot lower risk than vaginal or anal sex.
The most common infection resulting from oral sex is NGU. This is an infection in the urethra that can be caused by normal mouth bacteria that gets into the urethra during oral sex.
You could also get gonorrhea if the person giving you oral has gonorrhea in the throat.
Syphilis and herpes type 1 (cold sores) can also be transmitted vial oral sex (if you got herpes from oral sex, you'd have genital hsv1), but it doesn't sound like this is what you have since you don't mention any sores on your skin.
It could be NGU, and it doesn't really sound like gonorrhea. Your best bet is to get seen by a doctor. They'll likely have you pee in a cup, and test it.
You aren't at risk for HIV from getting oral sex (or giving it, either). Chlamydia can, in theory, live in the throat, but most experts say they've never seen it.