I had sex with my boyfriend 3 days ago (with condom) for the first time in about a year because I go to college in a different country and I'm home for the summer. Since then, I've been nauseous all the time, eating, and sleeping alot. I know I'm not pregnant because it's way too early to have symptoms, and it happened before after having sex after a long period of time, but i took morning after pills the last time to be safe. I just wanna know what can it possibly cause it.