Baby throwing up formula ( any kind) & not breastmilk. HELP

Sorry long post - pls read.After my baby’s he was fed formula( enfamil )and breastmilk (50/50 ) for first 2 weeks. Since then he’s been fed exclusively pumped breastmilk through bottle. As I needed to travel I wanted him to be ready to have formula when needed. So at month 2 I fed him formula and he threw up all of it through out the day( up to 3 hours after formula feed.) .

Mammas I need help, as I do want to have the option to feed him formula when needed. I have tried all formulas ( soy , gentle etc ) he throws up all of it. Pls suggest or let me know if this has happened with anyone? He was fine afterbirth with formula so why now is he throwing up ?