My baby is 10 weeks today. We switched him to Similac alimentum about 2 weeks ago. He has stopped fussing while eating. But now has what seems like slimy spit up. After he spits up he starts crying and trying to get all the left over spit up out of his mouth. Sometimes while feeding or after burping he will choke to the point of tears. This happens even when using the size 0 nipple. Would this still be caused by the acid reflux? Or is it now the formula causing this? Baby has an appointment tomorrow. But it's stressing me out. Has anyone had this happen?