Good morning all. I have a question about my 4 month old pup who started vomiting this week (has not done it before this week, at least since we've had him). Monday evening he threw up shortly after dinner, but before eating his dinner, BF let him chew on a stick in the backyard (BAD BF!!), so we thought he might have ingested some pieces of wood and that might have been the cause. The next day he threw up again after breakfast. This morning, he did it again. It's not always right after eating, so I'm not sure if its his food or something else. This morning, it happened over an hour after he ate breakfast (oh, and he couldn't do it on the floor, no, he had to throw up on the couch, of course!).
His poops are solid and consistent (he poops on a pretty regular schedule), and he hasn't changed his eating or drinking behavior; his energy levels are normal for a crazy energetic Lab puppy. 
He seems completely fine after he throws up (and, ugh, he tries to eat it afterwards...yuk!), and does not throw up after every meal, only occasionally, but this has been three times in one week. Any ideas here, or should I just go ahead and call my vet?
I did change food brands recently, but I mixed the two brands for several days before moving completely to the new brand. I'm thinking maybe this is the cause. Does anyone have any suggestions on a good brand for a 4-month old pup? I know every dog is different, but if anyone has had success with any certain brand in their puppies, I'd love to hear about it.