My son, 20 months old, suddenly dropped 4 lbs in 5 days. He has been taking longer, more frequent naps; at times it has been impossible to rouse him. (he fell asleep on the floor while playing by himself the other day and my husband shook him, rolled him over, even held him upside-down in an attempt to wake him up, but he couldn't keep his eyes open. He even stayed asleep during his diaper change!) This is incredibly unusual, as he has always been difficult to put down for his nap or bed. When he's not falling asleep, though, he is running around, screaming and laughing, and seems to have 2x the energy. His appetite, too, has been going from one extreme to the next, from wanting to eat constantly to seeming totally uninterested in food, even sweets and (his absolute favorite) mashed potatoes. He has been thirstier than usual, even though the weather outside has been cooler and wet, not hot and dry. at around 12 months of age, his stools began to become more solid, but at around 16 months or so, they became softer, then very loose. The doctor said that as long as he has consistent stools it is not a concern, but I'm beginning to think it may be a symptom of something more severe. The weight loss, appetite, and sleepiness has all changed in the last two or three weeks. Am I overreacting, or is my concern justified?