Help!

Tammy • Married💍; mommy to 2 crazy boys. Pregnant with my babygirl finally!! due June 2021 .

My baby boy was a preemie at 32 weeks weighing 5 pounds he was in the nicu for 2 weeks. He is a month old now. I was pumping a lot while he wasn’t here and as soon as we got him home my supply is barely anything so we had to supplement with formula. Well now a few times all ready he’s thrown the formula up to the point it’s coming out his nose and mouth and he gets bright red and can’t breathe. I pat his back and suck the stuff out right away and he ends up being ok but it’s seriously the scariest thing ever and I called the ped today and have an appt tomorrow am but she didn’t really say what it could be on the phone just to see if he continues doing it to call back right away. I’m just wondering what anyone thinks it could be?