WoW !!!!
Put Your baby down for low sugar is soooooooooo crazy I would find a new Vet for sure.I pray for Your new little guy and as hard as it may be,back at His old home with mom is best ! Even if She is not feeding Him.The stress of a new home was just to much
Back at His old home is less stressful and He is familiar.Just Be real patient and wait a few more weeks and try again,I promise it will be sooooo well worth it

As hard as it is.
Good Luck and Please keep Us posted