My 4mth old is predominantly bf with 1 or 2 formula bottles a day. He's got reflux and if very spewy. He'll be on the boob then with no indication beforehand will spew even when he's still on the boob! Why does this happen? He doesn't do this when he's having a bottle. I've been told to give him children's mylanta 1ml before and after a feed and he has lactose free formula.