Pop her little butt into a dog crate in the garage or house. Give some good warm food.Continue to observe to see what if any meds you can give. When they show signs of illness they go pretty darn fast.Atleast it has been like that with my hens and other roo. I have dealt with 2 rattle breathing,booger sneezing hens and a prolapse successfully.Had one die.Found one dead.Had to kill one.Dealing with a buldge on one.Always something!
Hope you can help her heal.Like you said maybe she is broody.Never had a broody,but I don't recall them laying on their side.Never know.Healings!!!!
How is your hen doing? They go pretty quick once they stop eating and drinking. Did you try any meds to see if it improved her? I just had to kill a hen the other day.It wasn't so bad,but I way prefer them dying at night on their own.
When my 2 had the upper respitory I gave whatever I had on hand,and either it helped or they recovered on their own. I gave oats and scramble eggs when I had sick ones in the crate. Healings!