Somebody please help

Rachel

I’m getting a really bad feeling about my LO. She has only been eating 2.5 ounces at most every 5 hours and she used to eat 4 hounded every 2-3. She sleeps 10 hours through the night with out waking up for a feeding. She threw up an extremely large amount on Friday night, & then about the same amount, maybe less, today. Does anybody know what could be causing this or what I should do?!