guys help please

Ok so on the 30 me and my boyfriend had sex and he came in me. He went that night and got me a plan B. 2 days before this my period ended and it wasn't a normal period. Now I'm bleeding again and it's light but I don't feel like me I'm having constant hot flashes and nausea I know you can't tell right off the bat but could this be the start of an egg becoming a fetus. I need help??