dog suddenly dies vomits blood

[nikkibonbon]

our dog is a lab hound dog mix. 8 years old. he never eats hard food but yesterday we gave him some. then he had most likely to many dog treats. the hard dog treats that are white or dyed. this was all yesterday evening. he ate it all. was acting normal. then in the morning we find him laying in his vomit. that looked undigested except the dog treats were digested. my husband said there was slight blood in his vomit. im pretty sure the dog had no diarehha or poop at all with blood in it. only blood in the vomit. his stomch wasnt enlarged looking. hours after putting him outside he stared to have labored breathing. he wouldnt eat or drink with slight foam around his mouth and wouldnt move. i believe he threw up his food that evening shortly after he gave it to him since it was digested very well. so he lived all night untill 3pm the next day. i told my husband numerous times i thought he needed to go to the vet but he didnt get him there in time. right after he died in the car blood which smelled putrid poured out of his mouth no pee or poop. what was wrong with him?