I Had My Period, But Nauseous?

Last monday(6th) I had sexual intercourse, and he came in me three times, my period was suppose to come on that wednesday, it didn't..It came on that friday..Anyway, last night I woke up (didn't know what time it was, didnt have my contacts in..) and I felt like puking, but I stayed on my back until I felt all this "spit" like coming up to my mouth, so I lean over the bed into the garbage can, and well you all those that "spit" like stuff that comes from your mouth before your about to puke.. Well that happened, I waked a while, and no puke. My stomach hurt so badly after that, and I just couldnt get back to sleep. Then today, my stomach has just been bugging me, and it's like I need "air"? .. I cant explain it. My period is medium, but in the morning I have alot of blood clots like usual...Im taking a test next week, but is there a chance I could be pregnant right now, when im on my period. I dont think two days before my period would have done really anything.. But could I be? Anyway, please post back, ive been wondering about this all day long!