prego or no

Hey I had unprotected sex last weekend (I know it doesn't matter but he didn't come in me ) and lately I've been kinda nauseous with some basic stomaches. Tmi but my farts have been god awful 😂 And my poop is so gross rn 😩 Help. I really can't afford to be prego I'm 15 ugh.  Is there a reason why this is happening ?