@brishti,
Are your hands exposed to any chemicals or poisonous plants?
You might want to keep a log of when the bumps appear, what your hands have been in contact with, the weather temps and humidity, your stress levels, etc.
You may discover a pattern to the outbreaks and be able to limit your exposure to the cause.
You say you've seen a doctor about it. Was this a dermatologist? If not, go see one. They specialize in skin disorders.