My ds is 4 weeks old. Sometimes he brings up milk after a feed, but other times he brings up milk between feeds which is curdled and sour smelling. He seems to constantly be blowing bubbles and have some of this curdled stuff in or round his mouth. Is this something to worry about? He gets hiccups a lot too, I thought he might have reflux but he is fairly content and doesn 't scream or cry in the way I have read about reflex babies doing.