Talk to General Physician on Possible Exposure To Std

My friend had unprotected sex he was afraid that he has been infected with STD. he consulted a doctor who instructed him to take HBSG, Hepatitis C antibody, HIV antibody test, and syphilis/VDRL test. Result of Tests was negative and HIV ag/ab value was 0.08 (non-reactive) considering this doctor suggested him to start taking HIV PEP medicine for possible exposure to HIV. he has been taking the med for the past four weeks. yesterday he took the test again the result for the test is HIV ag/ab value was 0.12 (non-reactive). As reading has increased is it possible that he has HIV and medicine are suppressing it. can any infectious disease doctor give his opinion on the above .