Early manifestation of HIV
can occur only after 2 weeks. Not earlier than that. So your symptoms are possible only due to ordinary viral fever
Anyhow unprotected sex with an unknown girl will have the risk. You can go for HIV screening after 12 weeks or you can have P24 antigen test as earlier as 3 weeks to rule out the possibility of HIV.
Try to stick to safe sex
always to avoid unnecessary tension and stress
Good luck to you.