DD is 3 weeks old and I have been BF on demand, this last few days she has started fussing 15 minutes into a feed, she will come off the nip screaming but want to latch immediately but her legs and arms are flailing and her torso is wriggling. I have tried winding and she may or may not burp, but she'll start indicating she wants boob back and she will suck for a minute or two and then fuss again, this will normally continue until we are so frustrated. She then won't settle down to sleep. It's not every feed that she is like this. I offer either boob, and milk is still coming out. She normally feeds between 15-25 minutes off one boob and often refuses the other if offered.
Is there a reason for this, am i doing something wrong? The start of the feed is normally very calm and she sucks enthusiastically and swallows well. Mainly feed with cradle hold by day and lying down at night.
Any advice welcome.