PEP treatment. I go for a 2nd opinion!

I had an unprotected sex with sex worker for one time. I asked her for the hiv status of her. She said that she has done 2 months back and it was negative. I took her to the hospital on that day itself and hiv test . It came back negative. But I consulted a doctor about it and he said to start pep treatment. He suggested to take raltegavir zepdon 400 mg tablets for 28 days. I started on the treatment on that day itself twice a day. But I started researching on google about the treatment failures. I am worried if in my case if it fails. When to get tested for the results. It's been 3 days taking the tablets. should I go for a 2nd opinion regarding the medicines. Please help me. I am so worried that I couldn't get sleep also