1) You can have a test at 4 weeks, if it is an 4th gen DUO TEST (P24 and antibodies). it would give you a 95% accuracy, then at 6 weeks and finally at 12 weeks, some guidelines say 6 weeks is conclusive, other say 12... it's up to you.
2)HIV can not be diagnosed with symptoms, you have to get tested. Next time, if you think you were at big risk of getting HIV, ( because you live in a place or region of high risk population, or something else), you can seek for PEP at an emergency room of a hospital, if you are within 72 hours post exposure. the the best recommedation is between 2 to 24 hours.
One week is too early for Hiv rapid test . You should get tested again 14 days after exposure with a 4 generation Hiv antibody / antigen test .
Also wanted to add that I’ve had diarrhea for almost a week now