yesternight my 3 month old was grunting while breastfeeding as a if is in pain so I lifted her upright,she burped and threw up all the milk. she did like this twice and then cried hysterically. she does spit up milk but it was the first time she threw up. it took me more than an hour to calm her down. she then had milk and slept for sometime. is it something I should be worried about. she is fine and playful now.