I've never done anything with a guy, but I think I have , maybe even HIV..?

I've never had or done anything like that with a guy, I'm saving myself for marriage. However my best friend is kind of slutty and had unprotected with three of the biggest mans around. And she thinks she has HIV. Well i made suchhhhh a mistake and we overdosed on DXM. My friend said I called him that night telling him how i wanted to my best friend and how we were going to do stuff? Two weeks later, what do you know, I have these 3 big red swollen painful bumps. on my . Also, after I pee, I stop but a slight stream trickles out for another 1-2 minutes or so. Then, I have an itchy-burning feeling afterwords for hours that make me feel like I still have to pee. I'm really scared, because she thinks she almost definitely has HIV and stuff because her ex just found out he does, (who she's had unprotected with) and she's been lightheaded and nauseous losing weight and stuff. Do you think they're just coincidental bumps and a UTI or should I be worried?