what can cause my period to be so late?

Ke

my period is now 10 days late, i got my period since the last time i’ve had sex (which was the beginning of last month) but this months period isn’t here. i can’t possibly be pregnant, can i? or is there another reason that would make more sense?

UPDATE:

i woke up this morning so nauseous but not able to throw up and my stomach is in so much pain.😣