I‘m sorry for troubling you with this. About 3.5 weeks ago I had an encounter with a commercial sex worker. She gave me a massage, we cuddled, and kissed closed mouth. We were both naked at the time and I had worn a condom, though during the session the condom had slipped off at 2 points before I applied new ones. At some point our genitals might have touched. 

And indeed that is the case. Even if your CSW partner has HIV, you could not have been infected in the contact as you describe it. With few if any exceptions, sexual transmission of HIV requires a penis to enter a partner's vagina or rectum; even oral sex is near zero risk. And certainly there has never been a documented cases of transmission by massage, body contact without penetration, or kissing, especially closed-mouth kissing. In addition, it is statistically unlikely your partner has HIV. I'm glad to hear the emergency clinic changed course and recommended you stop PEP, which clearly was unnecessary -- I suspect you requested it and they went along because of your fears. But for sure you didn't need it.  

As for your symptoms, they do not fit well with ARS, which doesn't cause the kind of rash you describe or any of the other symptoms.  That you "don't know" what other cause there might be has no bearing on the likelihood of HIV. Such symptoms are very nonspecific and could be due to any number of minor viruses, other health issues, etc. Some of them are suggestive of stress and anxiety, no infection at all.

Your next step should be testing for HIV. A negative HIV antigen-antibody (AgAb, 4th generation) blood test will prove your symptoms are not due to ARS (it is impossible to have ARS symptoms and test negative); and at ~3 weeks after exposure will be 90% conclusive you don't have HIV at all. You could then have another AgAb test at 6 weeks to prove with 100% certainty you were not infected.

I will be happy to comment further if you would like to let me know your HIV test result. Please be assured that recommending you be tested does NOT mean I believe there is any chance at all you have HIV; I definitely do not, and recommend testing solely for the reassurance you will gain from the negative result. So do your best to remain relaxed and unworried while you wait for the result. (But there is no point in further discussion until you have been tested. There is no other information you can provide that could possibly change my opinion and advice. So let's not get into any "yes but" or "could I be the exception" sorts of questions. OK?)

I hope these comments are reassuring. Let me know if anything isn't clear.

HHH, MD