Last night around 11 pm I was feeding my son he wasent done eating when he vomited everything out…

Last night around 11 pm I was feeding my son he wasent done eating when he vomited everything out ever since then he hasn't been eating right he usually takes 4-5oz every 3hrs and now he's just taking 2oz and falls asleep then wakes up in a hour and he's hungry I feed him he only takes 1/2oz ... Idk what's wrong with him 😕