What is wrong with me?

Since Saturday I've had a super dry & sore throat and really bad headaches. I haven't had a fever yet, the highest my temperature ever was, was 99.9. My stomach has hurt super bad too, but its a come & go pain. This morning at like 6:30 am (Eastern US time) my stomach started to hurt super bad and I went to the bathroom. I sat there for like thirty minutes and I had diarrhea. I've been having it for a few days. I really don't want to go to the doctor, I'm sick with strep like every month and my doctor gives me antibiotics. She gives me the same ones always and I'm afraid that my body will eventually become immune to them so they won't be so affective in the future and I don't want to be just living off of medicine. Does anyone know what this could be? Thanks.