So confused!

I had my period 4 days late, it was brown, never red. 
Last night (about 2 weeks later) not thinkin anything of it I took a shot of vodka with my boyfriend. Not 20 minutes later, I started feeling sick so I went and laid down. About an hour passed and I woke up with the sudden urge to vomit. I haven't puked in years and I'm not a "lightweight" Iused  to drink all the time. I don't get what's up with me. My boyfriend is always joking that "junior" is in there but I highly doubt it. Would somethin like this happen if I was prego?