others may be able to help you more but are you giving a little nutrical if not eating much? that might help as you do not want him to go hypoglycemic - did vet mention that to you as ours did when i got dex and the next day he got it
so i rubbed honey on his gums. You may want to get a tube of nutrical if your baby is not a big eater- how much does your baby weigh?