Armpits sweating for no reason?

im 14 and my pits begin to sweat at weird times. i wake up, go to school and from 8:30 to 12 im fine but once i get out of lunch they just start sweating, for no reason. Its embaressing and stressful, i cant raise my hand to answe a question or anything. is there a reason for this? oddly enuf i sweat more in school than when i work out. wtf??????