The ewe could producing milk ok now, just lambie is drinking it all, so not much there for you when you look, and why his belly is rounded in the morning.
Bottle fed lambs will
always run to you screaming for food, it does
not necessarily mean they are actually hungry
. I always feed until their tummy is nice and rounded, or they've had the ration I felt they should for that feed, whichever comes sooner
Maybe try giving him less in the morning feed, and see what happens?