Sorry for the delay in coming back.
This is for anyone who finds themself in a similar situation.
I was terrified after my encounter, as my original post probably showed! I started showing HIV symptoms including enlarged lymph nodes (mainy neck) and a completely white tongue, I heavily self-diagnosed anti-biotics hoping it was another disease - but this antibiotic over-medication i now believe was what caused my symptons to get much worse! Which in turn made me really believe I had HIV. From some forums i read at the time I literally thought I 99% had HIV.
I never had a fever though, and a fever is one of the most common symptoms as it's your bdy trying to burn away the virus - so that always gave me some comfort.
I flew up to Bangkok for 'rapid' HIV tests which turned out to be a waste of time, you really cannot tell for sure until at least 3 months. But you can be a very very high percentage sure after 4 weeks. The Thai Red Cross Hospital in Bangkok was the best at roughly 92% certain at 2? weeks.
After 3 months I found for practically certain (by modern medicinal standards) that I did NOT have HIV and I cannot explain the relief I felt. The experience did obviously spoil the rest of my holiday in Thailand and the next couple of months were hard, but i've learnt from the experience.
Even if you show symptoms early, you probably are ok as symptoms don't usually show very early. But be careful, and always wrap up! It just isn't worth the risk. Research I did showed that after years of decreasing HIV is on the increase again now because of slackening education. I also read (but cannot confirm) that the bar girls who travel with a westerner as a girlfriend are more of a risk than the actual sex workers who are more cautious.
Thai condoms are terrible and more likely to break or come off so I recommend bringing your own from home.
Really try not to be like me and let the symptoms get you down until you do have the positive diagnosis (but i know if anyone had said that to me i'd have ignored them). You don't have HIV until you have a positive diagnosis, and it is difficult (particularly for men from women) to contract.
And the biggest thing i learnt that helped get me through, is that HIV is no longer the death sentence it once was, in many countries the medical care is so advanced now that people with it continue normal longs lives. The stigma of it is terrible and people should be educated more so they don't judge so easily, but I guess the fear does help people remain more cautious.
Thanks for everyone that did respond before. I hope this post doesn't offend anyone. I only write it as I would like to have found it myself when i was having my meltdown lol!