Fussy while nursing at 4 weeks old

auburnbride2be

He's been nursing nonstop for a week now. I literally have nursed him for HOURS at a time. So the past few days, he gets frustrated or fussy while eating and cries. He then wants to go right back to nursing. I don't know if he's not getting enough milk fast enough or what it could be. He has plenty of really wet diapers and poops regular,y so I feel like he probably is getting enough milk. I don't understand why he wants to nurse so often and for so long. I have pumped a few times and there seems to be plenty of milk. Any thoughts/ideas??