I have a Gold Lab about 18 wks old I feed him Blue Buffalo food Since I changed to LRG breed puppy food hr thr?

To Lrg breed puppy food he throws half of it back up. Not suer about how his shots should go He has had 3 set set and a 7 in one so what is next. His he behide in shots and that has made him sick or is it the different dog food (same kind Blue but just for large breed puppies, I'm lost this is the first REAL dog most have been half breeds, so if you could help me with this without having a 500$ vet bill