Please help! How can i stop myself my sweating so much?

I am super healthy and fit, play heaps of sport and eat correctly. (15 years old btw) but i can't stop sweating under my arms and sometimes on my back. I use just normal deodorant because i've tried the clinical protection stuff but it didn't work and it was really expensive, so i use a non-clinical protection one just to prevent the smell. what can i do? will i grow out of it? it started in year 8 and now i'm in year 10. it's really embarrassing when everyday i sweat and especially on saturdays when my netball uniform is drenched. im also like the only one with this problem. also, at home in my pj's i never do. ??? please help. anything would be appreciated. thanks