My daughter is 3 years old. As of late she does not want to eat and as a result she is very lethargic and tired almost all the time, also occasionally she will say that her eyes are burning and stinging. Usually she drinks about 60-80 fluid ounces daily, craves salt excessively, and frequently during the day she bangs her head off the wall or on the ground for a few minutes at a time! She is our middle child, and yet at 39 months she weighs less than our 18 months old little boy. She looks malnourished, has dark circles under her eyes and her is very thin fine and not very long. She has been seen by a few different doctors but thus far NO ONE has been able to tell my wife and I what is the matter with her. Could you please help guide us, PLEASE? In the range of all possibilities, what could this be?