No from the level of contact you described (if the anal was fingers only and you have no fresh cuts on your fingers) and the sex was protected then no this would not be HIV.
Nonetheless not because of this specific episode but by good practices you should always find out your hiv status before sex with a new partner. That is ideally what one would do.
The night sweats were probably related to another, non sexually-transmitted, viral infection.
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I can discuss more if you need.
No these do not seem as severe as what one would experience.
They could be due to anxiety, yes.
But as per your first concern, this level of contact would not place you at elevated risk for HIV
Glad to help.