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High calcium is sometimes accompanied by low magnesium levels. Magnesium is vital to relaxing muscles, so the elevated calcium may be causing spasms.
There is a cream made for the autistic community, esp for children called Kirkman's magnesium. This cream has become very popular now, and not only autistic patients use it... the general public now is
using it to supplement magnesium. The fact that you can measure out a dose (unlike other lotions), is handy for use in children, and gives you control as to how much to use.
it comes with a scoop to measure out what you need, so is perfect for children.
This site gives the RDA for magnesium for children and adults.
Since you say your child is a poor eater... it is likely she is low
in the mineral.
8.5 yr is right on the borderline for a big jump in magnesium needs. Magnesium is needed for over 200+ metabolic processes and typically low in people in the US. 70% in fact appears in some studies now.
You could rub the cream on her back at night (this promotes restful sleep as well) and see if the spasms abate.