+ HPT then AF in same day

Approx. 10dpo started with very light brown/light pink spotting for 3 days, stopped for almost 48 hours hpt this am showed faint positive felt sick this afternoon with upset stomach ended up with diarrhea. Within an hour of diarrhea, full blown period - heavy cramping and heavy flow..thoughts?? I'm used to heavy painful AF but it is unusual for me to do this. Usually have light start into heavy and back light....been TTC 5 months 1st ever +