Stomach kills

So the last week of November I had a yeast infection and my period at the same time. Now I’m struggling with a really upset stomach. It hurts in the lowest part of my abdomen it’s kind of a burning feeling. Sometimes I also feel nauseous. Ive tried some tums but it’s not helping. I’ve had this for almost 3 days now. I have a boyfriend but we’ve never had sex. So i I don’t know what to do. I don’t know what it’s could be? Help! Thanks!