Does he eat multiple times a day? If so does he keep his other meals down? If he is only fed once a day try to split up his food so he eats 2 or 3 times a day.

Do you feed him the same time everynight? if so maybe try to feed him a little earlier or later, maybe he just feels off at a certain time of the day.

Nutro is a good food, but again not for everyone, maybe try a different food or at least nutro natural instead of max.

Is there a certain kind of treat he gets at night? Maybe that is the cause?

Is his food still whole when he vomits it back up? If so he is probably eating it too fast, again multiple small feeding throughout the day should help.

Is there any activity he does everynight? Maybe he just can't eat after he gets a lot of excersize?

How old is he? How long has he been on Nutro? Exactly how long have you had him & how long has he been doing this?

What did the vet reccomend? What did they test for? Did they ever give him any meds or anything for this?