5 week old DS is currently fed mainly with expressed breast milk (due to not gaining weight in first few weeks we had to switch to this from breastfeeding as he would always be still hungry after breastfeeding for over 40 mins). He has the occasional formula top up when we have ran out of EBM. This morning he is pulling faces when trying to feed, as though he doesn't like the taste. He will reluctantly take the milk if I leave the teat in his mouth for a few more seconds, but has only taken 30-60mls each feed overnight and this morning (normally takes 110-160 each feed). He is showing signs of hunger when I have tried to feed him. Anyone had experience of this? Is it something I have eaten?? Can he taste the steriliser? (does smell a little soapy or something) Milk is stored in the fridge for up to 6hrs before it is given so I don't think it can be going off in that time. Any advice much appreciated! Thanks