What to do if i am 16 years old and today after using my thumb a bit it started to ache at the base joint. is this normal from just overuse?

Body talking: It's your body's way of telling you "cut out what you are doing". Learn to listen to your body as you go through life - it will help keep chronic injures and pain to a minimum. So, yes, it is likely just an overuse irritation that will settle down in a couple of days if you don't repeat the stress. For now, put some ice on the area and if really uncomfortable, take some ibuprofen.