Is it just my head playing tricks on me?

You guys lately i cant eat. I mean. My stomach feels weird and nausaes. In the mornings it feels weird, i cant eat alot with out feeling weird or get hot flashes. Around the begining of the month my boyfriend and i messed around in the nude but we never had sex (read all about pre cum and all that AND im on birth control) the next week i got my period. But since then i couldnt eat! Is it my head thats worrying me? Nothing feels different but that? Is it just my anxiety? Some one please help. I take my birth control everyday have not missed and been on it for three to four months. What is going on. No i havent taken a test but i had gotten my period. Please help.