Quick question

Armani
So my app said I would get my period this last Friday, (I tested 3 days before that & i got a BFN!) I didn't really see any bleeding till 7pm & it was very light. Saturday (yesterday) i went xmas shopping I could feel the cramps really bad, & i was bleeding medium. That day i was experiencing nausea, severe diarrhea, & cramps.... I ended up throwing up what I ate all day. Today Sunday i woke up, my bleeding is super light i wont see any blood on the pad but when i wipe i do, cramps are mild but diarrhea & nausea are still there. Every time i stand i feel light headed & want to throw up..... Could this be bad? Could this be bc my period? Can I be pregnant? I don't have a fever or anything else... What do yall think?