I would watch her in the morning and just see if she is going out to roam, and eat and drink. You can insert a clean finger 1-2 inches into her vent to check for a stuck egg. Feel of her crop early morning to make sure that it is emptying. Chickens are good at hiding symptoms of illness, but many start out separating themselves and acting lethargic, or have a poor appetite. At 3 reproductive issues may be more common.