My son is 4 weeks old and i breast feed and supplement with formula due to lactation supply issues. Today he has been eating every hour or so, and taking down about 3oz of formula at each feeding. Normally he drinks 2oz or less (plus bm). The last 3 hours he has been drinking nonstop, about 8oz plus bm, and as soon as we take the bottle away he starts rooting around and sucking on his hands. He acts ravenous! Just a few mins ago he threw up/spit up a few times then immediately passed out asleep, finally!.....is this normal!?