One of my baby lovebirds don't gain weight recently. He is 23 days old and weigh 31-32g.
I feed him 10-12% his weight every 4 hours but his crop not emptying to next feeding sometimes. Usually there's a bit of hard formula on the bottom of crop. In such situation I give him warm water with a little bit of vinegar apple cider and make a crop massage. After that his crop is empty nicely.
He isn't lethargic, he still has an appetite, run and chirping, pooping like always. All is same as always except the not gaining weight and problems with crop sometimes.
Of course I will go to my vet soon. She is not avian vet but it's better than nothing.
I'm really afraid that my baby may have some crop infection.

Question to people with experiance with hand feeding: Do you ever had such situation (Not gaining weigh)? What was a reason? How you resolve it?

Food: KAYTEE - Exact Handfeedning Universal
Brooder temp: 33-34C (91-93F)
Food temp: 39-40C (102-104F)
Baby age: 23 days
Weigh: 31-32 g

Thank you in advance