I am demand feeding Ben. Up until the last week he has been feeding every 2-3hrs during the day, last feed at about 9/9.30pm and only feeding once between then and 6-8am. This was great and he was sleeping well between feds. He was only up for about half an hour (unless I was delayed in getting him down by doing something with/for Jack) as he would be tired quickly.
During the last week he has hardly slept between feeds during the day, sometimes only sleeping 10-15mins at a time then me putting him back to sleep. He has been feeding about 2hrly, sometimes 1.5hrly! The longest he will sleep is 45mins but not often.
Why is this happening? At first I thought it might be his 6wk growth spurt but it has been happening since Monday afternoon (or was it Tuesday?

), I am sure a growth spurt doesn't last this long, does it? I am getting him down when he shows tired signs. Mum suggested it might have been his jabs which he got a few days before this started.
Any ideas on why this is happening?