I will not comment on the issue of possible Lyme disease here as it is far off the topic for this forum other than to state, as was mentioned in your exchange with the members of the Lyme community, being tested for Lyme disease was a bit of a fishing expedition by your doctor whom, I presume was being thorough. Lyme tests are two stage tests and prone to false positive results. Irrespective of whether you had Lyme or not, you took therapy and now have a negative test. (I will not comment further on the Lyme disease question).
I will however comment on your STD and HIV risk, starting with the bottom line - you have nothing to worry about. First, with respect to the STDs, you have been tested and have negative tested. the tests are very reliable and can be believed. In addition, if you took the doxycycline after your last unprotected sex, even if you had gonorrhea, chlamydia or syphilis, the doxy would have cured it. Thus there is no reason at all to worry about STDs.
As for HIV, again there is little risk. Here are the reasons:
1. The odds that your partner, a heterosexual male, was HIV infected are very low - less than a 1% chance unless he had other risk factors.
2. In the unlikely circumstance that he had HIV, your risk of getting infected is no more than 1 in 1000, again very very low.
3. Finally, you had a negative test more than four weeks after your last unprotected sex. At that time, the test would have detected 85-90% of all infections acquired 4 or more weeks earlier. When you put all of these factors together, it is clear that your risk for HIV from the exposures you describe is close to zero.
Lastly but not least, your symptoms are really not suggestive of recently acquired HIV.
There is really no need for further testing. You need not be concerned that you have acquired HIV or other STD from the exposures you describe.
Hope this helps. EWH