Molt can sometimes set up a vicious cycle.
Firstly, molt can wreck appetite and after not eating enough over several weeks, energy reserves take a dive. The result is lack of energy at best and starvation at worst. The outward symptom of the latter is extreme lethargy and the chicken often...
I must have missed that information that she's eating well despite being sleepy. No need to tube feed a chicken that is eating normally.
There are so many factors needing considering when diagnosing a sick chicken that we can only make logical guesses and rule things out.
It would help to...
Before we jump directly to an antibiotic, we try to rule out the most obvious, easily treated issues first. That's why I suggested tubing her and getting immediate nourishment into her. If she appears to be much improved within 24 hours of nourishment, then we might be able to rule out infection...
She could be ailing with an infection, we don't know, But molt does sap a chicken's energy reserves, causes poor appetite, and some chickens become too weak to eat. Tube feeding to get a molting/starving chicken strengthened is what I do first,
Then I feed high grade animal protein every few...