Embarrassing sweaty hands? Please HELPPP?

I'm a 15-year-old female and since the age of around 4, I've had sweaty, clammy hands most of the time at school and sometimes at home. I went to the doctors when I was about 7 and got this roll-on stuff which, if I'm perfectly honest, I refused to wear regularly and I can't remember if it helped. More recently, it has been getting much much worse. Whenever I'm standing in class, we do cooking, they are very wet and they are red. It's embarrassing becasue, if someone takes hold of my hand then they will feel it, or at least, I think they do. They are not always so bad that they are red but they are rarely completely dry either. Does anyone know any things that can help this that are suttle?