Yes,broody hens just sit and poop only a couple of times,huge poops. They do not eat properly. Does she growl or make funny noises when you approach her?
So there is no wound,just feathers missing? Is it cold where you are,this might explain black tips on comb(frostbite) or respiratory issues...
Clarify a few things,you posted she had diarrhea,but was only pooping 2-3 times. You mentioned in above post that rooster had pecked her,is there a wound? You mentioned she had a black comb,explain.
Could she be broody? Is she eating/drinking?