I am scared and think i might have an std

Hi im 17 and i have been with this guy for almost 2 years... actually it will be 2 years march 18. I am really scared... i had surgery and got my apendix out and after that i didn't have intercourse for about a month... then when i got better i had intercourse with my boyfriend... recently i have gotten red bumps on the outside of my lips but it is on it... i am really scared that i have an std and i dont know what to do. it itches alot and i can't stop thinking about it and it is making me sick to my stomach. if i could please get some feedback that would be wonderful... im really scared and im just wondering what it could possibly or what.. i know that i have cysts on my ovaries and i was wondering if this could be cysts on my lips and if not could it be an std. !thank you!