Am I Safe Despite Persistent Headaches After Negative HIV Tests At 43 And 48 Days Post-exposure?

Hi. I had protected sex with a prostitute about two months ago. Started having regular headache after 20 days of possible exposure. Got tested for HIV 1&2antibody at 43rd day and it was non reactive. Got myself tested again with a fourth generation antigen antibody combo test at 48th day. It was negative with the p24 value 0.45. The chronic headache is bothering me so much. Am I safe? What could be the cause of this sudden persistent headache?