Not sure why?!

Ok so last week I had unprotected sex like twice. He wasn't close to coming or anything and it was only for like 3 minutes each time cuz I realized what I was doing and I knew it wasn't smart because I'm not on birth control. I was a little worried but not too much and I had like 3wks before my period was supposed to start. Well my period started last night. It was really sudden and I'm never early it's always regular. A few days after having sex I had been feeling sick and I work in fast food and the smell and people ordering certain stuff made me feel more sick than normal. Is it possible that this isn't my period but a really early miscarriage or something? Idk what's going on. I've never had this happen before. Someone please help?