Whats wrong with my chicken

[Dannis_chickens]

2 days ago one of my chickens started to fall over when she was walking. I've tried googling but I can't find anything. Her comb is still standing up right and nice bright red, she still free ranges all day, she's eating and drinking normally. But she falls to the right when walking and looks a little puffy and her wings look like they are hanging a little low! Does anyone have an idea what's going on and way I can help her!?

Thank you

 

[Eggcessive]

Is it hot where you are located? Is your coop well ventilated and in the shade? Can you get her drinking some water with electrolytes in case she is dehydrated? Is her crop full tonight, and is it firm or squishy? Does she seem to have a lame leg?