This is just anxiety and stress. i suspected that my barber,and i have been a customer of the barber for a year and a half, did not change my razor and i did hiv combo test after 21 days result was negative.should i relax and forget about it or what?

No, negative result at 21 days post exposure is not conclusive. For a complete assurance, you should have another RAPID combo test at or beyond 90 days post exposure. If you have test with the lab (blood draw) instead, negative result after 45 days is conclusive. You can read this link for CDC guidelines - https://www.cdc.gov/hiv/basics/hiv-testing/hiv-window-period.html

You are right that it is likely your health related anxiety and that will have to be addressed with the help of your doc.