Concerned About The Chick In Cage #2 :-/

This chick hatched on approximately January 1 or 2, but is much too small to be 7-8 days old.  The parents are feeding it, and are keeping it warm, and it's begging much louder than it was a few days ago, but its physical development is too slow.  I've started handfeeding it supplementally, while letting the parents continue to care for it.  Good thing it's the only hatchling in the nest, or its siblings would've outgrown it.  I don't see anything physically wrong with it, but that doesn't mean there's nothing internally wrong.  Unless it starts gaining some size in the next couple of days, I'm afraid it's not going to make it.  :-(

Update 8:30am - I went to feed it again before going to bed, but this time it didn't want to eat. It had completely digested the handfeeding formula from earlier, and had a tiny bit of food from its mom in its crop, but I could only get a very small amount of handfeeding formula in it.  It should have been eager to eat.  Maybe it'll surprise me, but I'm not optimistic. :-/

Update 7pm - It had a tiny bit of food in its crop from its parents, but its skin looks dry-ish.  I tried to handfeed it again, thinking it was becoming dehydrated.  I was only able to get a little into it, about half as much as the photo above.  The parents are still feeding it, although I wish they'd feed it more, and they're keeping it warm, but I'm still worried.