Sweating while playing & physical activity is normal but in case ur child is sweating excessively that is worrying u....can be due to vit D deficiency also....ur child is in growing age & may require supplementation with vit D & calcium ....

If you are worried about your baby sweating constantly, it may help to know that this is a normal process, which may last until he is about four years old. Sweating on the head, especially during sleep, is very common in children. Sweating in the palms and soles is also common during stressful situations or in enclosed environments, such as shoes or coat pockets. Underarm sweating is usually caused by hot environments and anxiety. If you may notice that your baby becomes sweaty sometimes, just relax and change his clothes if necessary