Hi Doctor, I Am 37 Years Old Journalist Living In

Hi Doctor, I am 37 years old journalist living in East Africa, I have white spots on my skin, mostly on my back, shoulders and neck, they always increase when I am in a cold whether and they grow very speedy, they cover 50% of my upper body now. What is the cause and how can I treat them? PS: We don't have dermatologist in Somalia.