After A Possible Exposure(unprotected Vaginal Sex) Having Had Sex With

After a possible exposure(unprotected vaginal sex) having had sex with a lady whose status I dont know ..at about 3/4 weeks after the encounter I started experiencing diarrhoea which lasted a week and lower part abdominal ache...this prompted me to go for a rapid hiv antibody test using determine and it immediately showed a reaction but faint line on patient area and it remained faint after 20 min...and the control line was bold enough. Now am scheduled for a confirmatory test... I am so worried and stressed... could there be a chance it's a false positive?.. or it's certainly apositive hiv diagnosis for me?...and what do I do?