The signs are all there this is a failure to thrive chick. If the chick is going to make it, you will see it improve from this point on. If the chick is not going to make it, it will decline from this point, no matter what you do.
In fairness to yourself and your sanity, as overwhelmed with life as you are, I would set Friday as the reckoning day. If the chick shows improvement each day from this minute on, then by Friday, it should be obvious it's likely going to make it. If no progress is occurring, by Friday you will know this with virtual certainty. Then you will take the necessary steps to end this ordeal for both you and the chick.
This is not easy. But setting these goals and knowing what you will do, and knowing that one way or another that this struggle will end on Friday, come what may, will be very helpful in keeping yourself from falling off the edge.