Listless, shivering, shallow breathing

Sorry about your pullet, but so glad that she seems to be perking up. How old is she? Has she ever laid an egg yet? She looks pretty young though. Could she have been injured by a rooster or others? Besides cooked egg, most chickens will peck at chick feed made wet with warm water, tuna, and canned cat food. Those can get more fluids into her. What do her droppings look like? Coccidiosis could be a concern if she is having runny poops. That is treated with Corid, but I would continue to water and electrolytes, or some Poultry NutriDrench.