Symptoms of too much gaming?

My second joints (no idea what they're called) are slightly large and my wrist sometimes feels sore after a while of computer or when i just get on. I think i might be developing carpal tunnel but im only 14. i am wondering if i actually am and how i can prevent it . I also play tennis a lot too which may also contribute to it. also, are the enlarged joints a sign of over gaming or genetics?