I've Had Sex And I Haven't Check If I Am

I've had sex and I haven't check if I am but I've been vomiting sometimes when ever I eat even when I don't eat so it was normal vomit but now it's white foam coming out of my mouth just like that and I don't know but I also try dieting but I've notice my stomach have been getting round as big but not that big, I don't know what my problem is and am sure that am not pregnant but feel like I am because I also have stomach pain when ever I try to sleep. I didn't missed my period because it came last month and end very early. What could be my problem?