Dog owners help please ☹️

My puppy will be one in December. He was the runt. He’s always been a laid back, chill puppy. So him moping around and being lazy wasn’t ever something that worries me. But now I’m concerned.

He isn’t eating. He’s supposed to be eating at minimum twice a day. We split his daily portion into two. Once in the morning before I head out to work. And again around dinner time. On occasion if he ate all his morning food, my husband would give him a new serving around noon. But that never really happens because he won’t eat.

There’s days when he’ll have his morning food there until night. It would literally take him ALL day to eat it. We tried mixing it with canned food and even warming it up a little. At one point we had to start spoon feeding him and we got him a high calorie vitamin booster which helped him gain some weight. We changed his food. And still hardly ever eats.

I don’t know what to do. He’s throwing up yellow foamy bile now at least once or twice a day. I’m so scared. He has a vet appointment next week. Have any of you ever dealt with this??? This is my baby Mio.

He isn’t underweight right now thanks to the high calorie booster but his eating habits are really concerning me.