I have various pains in my legs during the night. The treatment is dependant upon the cause really.
Part of mine is circulatory, so I have to sleep with my feet about 6″ lower than my bottom (I have a hospital type bed that I have permanently in a downwards tilt), so that gravity aids the circulation of blood to my feet. You can improvise by raising the head of the bed on blocks, or sleeping with pillows under her bottom.
The second problem is caused by my tissues being too fragile on my lower legs, they don’t withstand pressure very well. So, if I go to sleep (or wake up) with my ankles crossed, I am in pain, my legs also feel very sore at the point of pressure and it takes a while for the discomfort to dissipate. I have to be very mindful NOT to cross my ankles. At one point, even the weight of the covers caused the soreness but, thankfully, this no longer happens.
I have to wear smooth legwarmers 24/7 in order to keep my legs warm, as the cold can trigger pain too. If this is the case for your daughter, what about using an electric underblanket, on very low overnight, to try and maintain a more ambient temperature for her legs.
Pockets of fluid collect in my legs (confirmed once when they suspected a DVT), I’m not 100% sure but I think this is likely to be lactic acid. I have my lower legs massaged with Diprobase cream at least twice a week and this helps improve this condition, I suppose through lymph drainage and helps repair the dry skin there too. Maybe you could massage your childs legs before bed ?
Throughout the day, if I am sitting still for any period of time I repetitively curl up my feet, or lift up my heels, or rotate my feet, or jitter my legs, to help improve the circulation. You may have noticed your child fidgets a lot. It’s ok, we can do this when we are awake but in the night we don’t have this option and I think part of our condition is that our brains forget we have limbs, unless we move them!
I hope some of this helps.
Head & Neck Injury (June 2002); Mild Concussion; Post Concussion Syndrome; Postural Orthostatic Tachycardia Syndrome (POTS); Peripheral Vestibular Dysfunction; Mild Radiculopathy & Small Fibre Neuropathy (right leg & foot resp.); Partially Empty Sella (Oct 2002) Fully Blown Empty Sella (Oct 2004); Whiplash Associated Disorder (WAD); Cerebellar Ectopia (Chiari 0); Cranio-cervical Instability (CCI) with Posterior Gliding (PG) & Cranial Settling (CS); Brain Compression; Retroflexed Odontoid; Stretched/Elongated Brainstem; Vitamin D deficiency; Ehlers Danlos (EDS) type 111; and now Osteoarthritis!