We have had two incidents with our son. The first was very similar to yours. We got him up and he was very stiff, if we lifted his arm it just stayed there! I fed him his morning milk, tablets etc (he was very young) and over a period of an hour he 'wound up' to being normal. It was low blood sugar that caused that, he had no temperature. He did have a febrile convulsion at about 1 year with a high temperature. He shook and his eyes rolled. It was frightening to look at, but they are very common in kids (not just CAH kids). We haven't had another and he has not had any problems from it. I think your doctor is right, it will only be a problem if it re-occurs. Just make sure that if your child has a temperature you keep them cold. (Wwe have had our little boy sat in a luke warm bath in the middle of the night to cool him down if he's very hot!). It looks frightening, but really does them no harm if it's only once.