Growing pains. This could be growing pains. Growing pains are inflammatory areas on the end of bones (apophosytis) commonly in the knee area, heel area or even various other regions in the body. These occur from stress to these areas while growing. Rest, ice, and nsaids such as Motrin can help. Also important is stretching exercises around the joints to relieve stress to the apophyses.
Loss of cell energy. Cell needs glutathione which gets depleted quicker with high energy needs for body supplement with n-acetyl cysteine helps with generating more glutathione inside body and relieves cell fatigue and pain.
Need glutathione. Our body makes glutathione but if energy needs are high we deplete this quicker taking orally vit b6 and supplement glutathione will help the pain. Glutathione precursor is nac which is available over the counter n-acetyl cysteine.