Newborn not pooping

R

Im a first time mummy so not sure if it’s normal but my 2 week old baby is constantly making grunting noises and looks very uncomfortable. I get him down to sleep and he wakes up not even an hour after looking like he’s in pain cause he can’t poop. He’s trying to push (make a bowel movement) but isn’t able to. He was having 2/3 poopy nappies a day 3/4 days ago but now he is hardly having 2. He had 1 during the whole day.

Im giving him breastmilk.