I'd limit the treats.
Make sure her crop is emptying overnight. If it's not, then
begin treating that symptom.
You can try vitamin therapy to see if those help. Give 1/4 tablet B-Complex and 400IU Vitamin E daily along with a bit of egg.
I'd also be inclined to give her extra Calcium for 3-5 days.
If possible, get a fecal float to see if worms are a contributing factor to her decline.
It could be injury, she sprained something, or she may be suffering from disease like Marek's. It can be hard to know what's going on unless you lose them and have a necropsy through your
state lab.