My Son Is 14 Years Old And Very Active. He

My son is 14 years old and very active. He gets sever muscle cramps sometimes during sports activities. (My younger son is 13, plays the same sports and he doesn't cramp at all) My 14 year old does sweat a lot. He is very healthy and eats well. I have him on a Magnesium, Coral Calcium and Potassium supplement. He also takes Thermo tabs (salt pills) as needed when it is really hot and he is sweating buckets. On days he has football games he drinks a lot of water and Gatorade, this seems to help, but doesn't always keep the cramps from happening. Any other suggestions? Thanks!