Hi there,
I saw your post and thought I had to respond! I feel your pain. My daughter that is now 9, started having these "growing pains" around the age of 3. I hate to tell you, but she still has them some, although much less frequently. Dr. says they are a very normal issue with children, and some kids just have much worse symptoms than others.
These pains kept her, as well as me and my husband up for many, many nights. We found several things that can relieve some pain, just depending on how much she was actually hurting that particular night.
-It seemed to be very relaxing to soak her legs in the bath tub in warm water (sometimes at 2 a.m.)!!
-Massages were always helpful, adding bedtime soothing lotion during the massage aided in sleep.
-They make some really great ice packs that can be purchased at wal-mart and walgreens,(they are not "children" specific)they are gel packs that are inside a cloth like cover so they are not too cold and achy and are about as long as an adult forearm.
*I'm not a huge advocate for stuffing kids with meds unless the really are uncomfortable, but on some nights she needed the following:
-Motrin seemed to work better than Tylenol for relieving the muscle pain.
-Benadryl - if you have ever had allergies you know how annoying uncomfortable they can feel, and in a similar way the muscle leg cramps feel the same. Some nights we would give benadryl which would help her sleep and aid in the comfort and stop the flintching and tightness.
(Of course, check with your doctor on these for dosage. DO NOT COMBINE ANY OF THE ABOVE MEDS.) I'm sure you already know that, but I just need to put it out there just in case!! Feel free to ask me any questions.