You are seriously overanalyzing the situation. The odds are strong your Thai partner did not have HIV (my understanding is that fewer than 5% of commercial sex workers in Thailand are infected at present, lower than several years ago). I am unaware of data that Thai HIV strains are more transmissible than others, but even if so, the odds are overwhelmingly in your favor. Being uncircumcised roughly doubles the risk of catching HIV if exposed--but doubling a near zero risk still means a near zero risk. On top of all that, PEP is over 90% effective.
However, I am not certain about whether PEP delays seroconversion when it doesn't work. I believe your negative 4 week test is reliable, but you should ask this question of the provider who prescribed PEP. He or she might recommend a final test a few weeks later.
The symptoms you describe do not suggest HIV or any other STD. Whether they are related to PEP or just anxiety, I cannot say.
Bottom line: Mellow out; almost certainly you do not have HIV. Follow up with your health care provider, though, and follow his/her advice.
Good luck-- HHH, MD
I'd stop focussing on the side effects for starters; while PEP can be highly effective it is also highly toxic.
As far as I know, when you've taken PEP the window period begins once the treatment finishes. So test six weeks after and if it's negative that would be fairly conclusive. However, conservative estimates advise testing out to three months.
I'm sure the doc will have a better answer for you. I don't know about the level of risk changing for sex in Thailand; I do know that HIV is a fragile virus that is difficult to transmit, and that with the PEP regime under your belt, I'd expect you to to come out of this ok:)
I have been in your situation twice, i.e. taking pep after what I perceived to be a risky encounter.
From the research I have done it seems that pep does not affect seroconversion and if it does, its not significant. Think about it, when you receive vaccination for a disease, you are given tiny amounts of weakened or inactive virus and your body is still able to produce antibodies. Same with HIV, I should think, i.e. if pep fails, and you are infected and antiretroviral reduces your viral load, this won't stop your body from producing antibodies, therefore, your test results would not be affected.
However, I am not an expert. There are documented cases in the early history of HIV where seroconversion was delayed. However, details of these cases are sketchy and could be disputed.
The take-home message for you would be that you 4 weeks result is very very encouraging even reliable.
Second, pep success rate is 90% as the good doctor has mention.
Thirdly, HIV rate for Thai CSWs are low as also noted by Dr. H and heterosexual transmission risk is also low.
Therefore, your risk is almost negligible.