Welcome to the forum. Thanks for your question.
I understand your concern about the symptoms following sexual contact with the new partner. However, you definitely did not acquire HIV. Almost certainly you only have a rather severe but otherwise garden variety respiratory virus. Antibiotics have no effect on any viral infection; they only benefit bacterial infections.
The modern, standard HIV tests always overrule exposure history and symptoms, as long as sufficient time has passed since exposure. No matter how high-risk the exposures seemed to be and no matter how "typical" the symptoms for ARS, your negative tests are conclusive in relation to the first exposure and nearly so following the second.
Oral sex is virtually zero risk anyway. OTOH, another possibility might be herpes -- the first oral infection with HSV usually also causes multiple sores in the mouth and often on the lips. However, strep-throat-like symptoms can occur, and the timing isn't bad. If your partner 3 weeks ago has either oral herpes (usually HSV-1) or genital (usually HSV-2), you could have acquired either virus by kissing or oral sex, respectively.
For those reasons, I agree with the doctors you have seen. You shouldn't be at all worried about HIV at this point. If the symptoms persist, you will need to continue to work with your doctors about the cause. But HIV simply isn't an issue here. But do discuss the herpes idea with your doctors, and if active oral/throat inflammation is continuing, have a swab test for HSV testing (preferably by PCR).
Minor final point: you cannot self-diagnose oral thrush. White coated tongue isn't the same thing.
I hope this information is helpful. I'll be interested to hear about HSV testing results if you do that.
Best wishes-- HHH, MD
This probably isn't herpes, just a possibility. I suggest addressing these issues if and when an HSV infection is confirmed.
Dr. thank you for the quick reply. I had thought a lot about Herpes recently. One more question though. If I picked up HSV-1 (thought I read that would have happened in youth) or HSV-2 ... can I transmit HSV-2 now anytime I decide to go down on a girl? Meaning can I give someone Genital Herpes even though it was given to me orally? Probably worth being tested for both or at least 2 to know for sure?