Hello! I read carefully your query and understand your concern. HIV is most commonly diagnosed by testing your blood or saliva for antibodies to the virus. Serologic testing (antibody tests) for HIV infection is a two-stage procedure. Initially an enzyme-linked immunosorbent assay (ELISA) is performed. If this is negative, then the test is negative. If the first ELISA is positive, then it is repeated. Only samples repeatedly positive on ELISA undergo confirmatory testing. There s a period of time after a person is infected during which they won t test positive. This is called the “hiv window period.” The window period can be from 9 days to 3-6 months, depending on the person s body and on the HIV-test that s used. During that time, you can test HIV negative even though you re HIV infected. So in your case if you did the test 21 weeks (5 months and 1 week) after the possible exposure to HIV infection and it result negative you don t need to worry you are not infected.No need to do further tests. The majority of people infected by HIV develop a flu-like illness within a month or two after the virus enters the body. This illness, known as primary or acute HIV infection, may last for a few weeks. Possible signs and symptoms include:Fever ,Headache ,Muscle aches ,Rash ,Chills ,Sore throat ,Mouth or genital ulcers ,Swollen lymph glands, mainly on the neck ,Joint pain ,Night sweats, Diarrhea. The symptoms you describe might be due to stress,anxiety and the fear you have of being infected. You can do another test after 1 month (after have been 6 months from HIV exposure ) so you can definitely exclude even a very very small possibility of falls negative result in first test and so you can rest your mind and don t think anymore about this. Hope my answer has helped. Take care. Dr.Rovena