From you history. There is a chance he might have dehydration. Because dehydration can cause blood pressure to fall and also will make the person feel tired. So check if he is taking adequate water during his sports activities. Look at his tongue and buccak mucosa if it is dry or wet with saliva. A dry tongue or moth indicate she might be having dehydration. Any way its is better to take plenty of water. Butter milk is better than water for dehydration due to presence of energy and salts. Also advice him to take lots of fresh foods rich in vegetables and fruits. Processed and packed foods are always not advisable for healthy life style.