A boil on your face. Do you mean a pimple that is festering? We all get those. Keep your hands off of it so it doesn't get infected as our hands even when we wash regularly can be dirty. With regards to HIV, though, this is not a risk. The only ways that adults get HIV is from unprotected vaginal or anal sex or sharing IV drug needles. Air and saliva inactivate the virus. The boil on your face would not be a route of transmission. You have nothing to worry about and no need to test.
Nothing. You were never at a risk. Please read through the FAQ section of this forum for risks.