2 days ago i randomly felt nauseous abd threw up, same day hour later i threw up again. next day i felt nauseous and light headed like i dont feel good at all. took 2 first respond test came back neg. as this happend to anyone?

my sister in law went to the doctors 5 months ago, took a urine test and blood work all came back negative. so she waited for her period to come but never did, so she went back 2 months after her first one. and guess what happend the doctor said, your almost 4 and half months .... but beside that, anyone in this room every experience this