Am not defending them but if it was that (could have been anything) could it have maybe been out of date? The house is such a state that they probably don't check anything an maybe refrigerating it made it worse, I only say that because years ago my cousin got a orange juice, said it tasted weird an threw up a few hours later, we got it back out the bin to see that it was out of date so had to go back into store the next day to let them know to make sure they removed any others off the shelf (sadly not the first time I've had to tell a store that products were out of date on the shelf, one time being pain killers)
I also hope that someone from the school sees the vlog an alerts them that they sent in the kid when they knew he had been up vomiting all night, I hope there's Karen parents there that kick up so much a fuss it risks his placement, it's about time consequences kicked them in the ass, they seem to get away with so much it's about time it caught up with them