Will Isotretinoin affect my HIV and syphilis tests?

Hi doctor,

I was taking Isotretinoin tablet from four months, and I stopped taking it. I had dry mouth, sores, thick line inside cheeks, some rough patches inside cheeks and lips also. But even after stopping Isotretinoin, I still have these problems. I have a lot of hair loss, nearly 300 to 400 per day. I also have a bump in the vaginal region. Whenever I search these symptoms online, it shows HIV or herpes. I am very scared. But, I took an HIV and syphilis tests after one month of possible exposure, which was negative. I again took the test after three months, which was also negative. Last month, that is after four months of exposure, the test was negative. But, most experts say that chemotherapy can affect HIV test. So, I think Isotretinoin can affect my HIV test to show a false negative. I am very scared of HIV, syphilis, and herpes. I am just 24 years old and planning to get pregnant. Please clear my doubts. What can I do?