Why does this happen?

i have an embarrassing thing happening to me. Exesessive perspiration. but the odd thing about it is tht its only in the winter months. im not fat so i dont have the issue with arm fat keeping air from getting to my arm pits. so i can only wear one color and thats black because its gotten bad. idk what to do. i would love to wear colorful clothing again instead of having drab black all of the time. HELPP!! please?