If the "possible exposure" is the same event you asked about last August, you were not at risk for HIV and did not need testing. In any case, it is not possible to have HIV and have a negative HIV antibody test (whether INSTI or any other test) 5 months after catching it. Your symptoms cannot be due to HIV from that event. See a health care provider if you remain concerned, but stop worrying about HIV.
HHH, MD