My son is a week and a half old and he's formula fed. It wasn't my plan for him to be formula fed so I didn't have any bottles. Luckily my sister gave us quite a few bottles and nipples that we've been using. He started on a bottle a couple days ago and the first couple of times he seemed fine but the last couple days he seems so uncomfortable after he eats. He squirms around and spits up, sometimes even 20-30 minutes after he's done eating. He's even gagged a couple times. I've tried gas drops and they do seem to help a little but he still has all the discomfort. He eats 3 oz every 2-3 hours and I burp him after every .5-1 oz. Could the nipples be too fast? Or could he have acid reflux?