Oh I know how frightening that is. Jake did something a lot like that because he woofed down his food. I'm not sure if Henry does this too, but it's a very common problem. We solved this by getting a slow feed ball and putting it his bowl.
They do appear to pass out when they can't breathe. Often Bully's do this while vomiting too.
As far as the food..Jake was put on Fromm All stages at 10 weeks. He came off Iams puppy food and directly (with slow transition) to Surf n Turf. We did change to Beef Fritatta because we figured out Jake and chicken are NOT good together! All Stage food is formulated for Puppies thru Adults. if I were in your shoes, I would make the switch to Fromm now. Just do it slowly giving his tummy time to adapt.