Lactose overload is sounding more like it. It fits in with what we experience. The suck-suck-cry-suck-cry routine, the ample weight gain & frequent feeding, and me thinking I'm not supplying enough! I'm going to try block feeding for a few days & see how that goes.

Barb - if it's something to do over supply, should I express less to discourage the excess? Or just keep doing it to have freezer stocks?

Thanks all for your replies. I feel like I'm a hamster stuck on a wheel in my own head - I need to join a mothers group asap! Only a few more days & the 'new parents group' starts.