My little one is 4 weeks old. I've become quite worried with his feeding. I exclusively BF. He is going great with weight gain, has 8+ wet diapers everyday, and poos every 2 days the normal BF baby poop. He only feeds for a couple minutes each feed, which is only one breast per feed. I have a fast let down. He then goes on to sleep sometimes 3-4 hours during the day and 4-5 sometimes 6 during the night. In between he gets very fussy like he is overly hungry, cries and wriggles but when put on the boob he pulls away. Then cries himself to sleep. He does spit up very often. Just very concerned as to what is going on.