Unprotected sex & paranoid having an std. In need of some advice please

I am a female 19yrs old. So me and my boyfriend have been together for almost a year. We had began having unprotected sex a month ago, no oral. Yes i know it was stupid of me to continue having unprotected sex. but then we had sex again since after the first time i had no problems at all. shortly after I began experiencing problems like nausea and server abdominal pain, I did consider the fact that I might have an std but then it turned it I began my period 3 days after so it was pre period symptoms. the idea of having an std still is on my mind and I have became super paranoid. But when i'm with him I seem to forget all my worries and act with out thinking and have sex again this time it was oral, I don't know if I am becoming really paranoid or my lip is a tad bit swelling up and i think i have a cold sore developing. I have my appoint with the doctor in a couple of days and nervous to find out. I just really need some help, if anyone has ever been through this? Am I being too paranoid and finding anything little thing and making it seem like a symptom? how should I bring this up to my "boyfriend" with out having him bale on me?