His CK test was normal -- it's not MD. THANK ALL THE GODS ABOVE AND BELOW. However, his TSH (thyroid stimulating hormone) was high, so he might be hypothyroid. He also might not be -- 70% of kids with a reading at his level come back normal on a rescreen -- but hypothyroidism can cause breathing problems and muscle weakness, and I'm hypothyroid and so is my mother, so it's really not out of the question. Fortunately hypothyroidism is quite easily and cheaply correctable, and even if he has a zebra instead of a horse (like if his TSH is high not because his thyroid is sluggish but because he has a pituitary tumor) it's still fixable, albeit with surgery.
After spending that hour in the Children's waiting room on Tuesday, a problem that, in its worst case, is fixable with a single uncomplicated surgery? I'll take it.