All of the above advice is great. Just wanted to add my 2 cents. I had growing pains all my life until I started eating a "real food" diet (eliminating processed foods and refined sugar), drinking filtered water, and taking cod liver oil two years ago (I am 33 years old). My leg pains would occur at night when I was young and whenever the barometric pressure would have a wild swing as I got older. I used to call myself "the human barometer"--I always knew when it was going to rain!
Anyway, we have had great success treating growing pains with eucalyptus oil. Add a few drops of eucalyptus oil to some coconut oil (or olive oil) and rub into the painful area. Simple but effective and works very quickly.
I would make sure she is getting good amounts of vitamin D--it would be best to have a blood test done to make sure her levels are good. If you want to have her levels tested, ask your doctor to order the 25(OH)D or 25-hydroxyvitamin D blood test. I'm not sure what lab your insurance/doctor uses, but I know LabCorp offers this test. You want her levels to be 50-70 ng/ml. Below 50ng/ml is deficient.
Fluoride toxicity can also cause joint and muscle pain. I strongly suspect fluoride in my case since I have other symptoms associated with fluoride hypersensitivity.