Great news, even though she is still not quite up to par, Katsu is getting up on her legs and trying to move around. She has been spreading her wings and using them as feet to get around, but this morning, I actually saw her stand up. She seems a little wobbly on them, but she stood!! Still don't know exactly what is/was wrong with her, but glad she seems to be recovering. She spends time in the yard with her sisters and the "hospital" cage has been relocated outside next to the coop so they can see her all the time. The other girls are doing great!! No sign of them coming down with whatever is ailing Katsu.
My Katsu is finally getting up and walking around!! Still don't know what her problem was, but she is happily walking around!! She does spend most of the day sitting around, but she will get up when needed. Her comb is a beautiful, bright red and she seems to be on the mend!!
Even though I don't know what was wrong with her, I am thankful for all the suggestions. Thank you guys!!