Welcome to the HIV prevention forum.
Oral sex is basically safe sex, especially for the insertive (penile) partner. HIV is rarely transmitted from someone's mouth, even when HIV is present, in part because saliva inactivates HIV. Some experts believe there is no risk at all; and another estimate suggests transmission once for every 20,000 exposures -- which is equivalent to receiving oral sex by HIV infected partners once daily for 55 years and maybe never catching the virus. The apparent injury during the course of exposure might elevate the risk, but even doubling an extremely low risk still leaves very low chance of infection (e.g. 1 chance in 10,000, equivalent to daily exposure for 27 years instead of 55.)
People with this level of risk really do not need HIV testing after individual exposures. Instead, it is best to simply plan on a regular HIV test every 1-2 years. If you haven't been tested recently, this would be a good time, since it is on your mind. But not because of this particular event.
Now I have to comment on "Unfortunately I do not know his HIV status as I was too afraid to ask after the incident". That was your first mistake, to not ask about HIV status BEFORE you got involved. Even though oral sex is basically safe, in the heat of the moment sometimes things go farther than intended, e.g. anal sex. It is very unwise for any male to ever have sex with another man without discussing and sharing HIV status together ahead of time, and either avoid sex entirely or be especially careful about safe practices for those who are positive, don't know, or seem evasive about it. Of course people can lie, but most do not; and of course someone could have caught HIV since his last negative test, but that also is statistically uncommon. Anyway, think how much less concerned you would be now if you knew your partner believed he doesn't have HIV.
Sorry for the lecture, but I take the chance to repeat this message every chance I get. Follow this advice -- plus condoms for anal sex with non-monogamous partners -- and you can expect to go a lifetime without catching the virus. Regularly ignore it and you're playing with fire.
Anyway, even now you should call your partner and ask his HIV status, if you know who he is and can locate him. You might find he is just as nervous about the event as you are and would appreciate your personal confidence you don't have HIV. After all, from a statistical standpoint he was at a lot higher risk for HIV from you than you were from him.
I hope this helps. Best wishes. And please get into the "do ask, do tell" habit.
HHH, MD
This situation does not warrant PEP. However, if you contact your partner and learn he has HIV, you might contact a local physician who understands HIV prevention. Opinions and guidelines about PEP vary from place to place and I cannot take responsibility for that decision in the event your partner is actually infected. (This is not "code" to suggest that I really think there was high risk; I do not.)
Thank you for your feedback Dr. The lecture is appreciated as I definitely acted stupidly. So I take it I should not seek out PEP after this incident?