My DS2 is 4 weeks old. Up to friday he was perfectly fine, not sicky at all. Since then he has been sick on and off all the time. It's not always straight after a feed (he's BF by the way) sometimes it can be a couple of hours after a feed, just before he's due another one, anytime really. He is calm and settled inbetween sickness, sleeping,feeding, pooing like normal.
I don't feel it's anything to worry about really, but could do with someone agreeing with me, or telling me what it is!