Oral on a prostitute

Alright, so I know this is probably a commonly asked question, but I'm asking anyway

I gave oral sex to a prostitute before we got into the other stuff. She was on the higher end of the spectrum so she seemed clean, but I'm worrying nonetheless. I know HIV is almost impossible to get from oral, so I'm not too worried about that. I am worried about the other stuff though

How likely is it to get STDs through oral sex? And what are the warning signs I should look out for in the next few weeks?