Condoms provide great protection against HIV and other STI when used for anal sex.
I know it can be hard when someone is really worried about a past sexual encounter. Just remember there are no symptoms that are caused by just having HIV. The symptoms people get with a HIV illness are common symptoms that can be caused by many different medical conditions. The only way to find out if someone has HIV is by doing a HIV test.
If you are concerned about the diarrhea you have been having I would recommend going to see a health care provider about this.
It is also common that many STI do not show symptoms, given this we recommend that people go for STI testing. How often you get STI testing really depends on your personal situation. Have a look at our page on when to test.
Also have a look at our “Know your chances” web page, it provides information on your chances of getting or passing an STI depending on how you are having sex.
Please leave a comment to let us know if this answers your question or if you need more information.
For other readers, please feel free to leave a comment, or let us know if this was helpful.