Please help me!how come precancerous moles/bumps keeping coming back on my shoulder blade?

Sun-related problem: Moles are often aggravated by sun exposure. Most folks exposed to excessive sun have more moles on their back. So it should be carefully examined by a dermatologist periodically. Use lots of sunscreen when you go out in the sun and avoid mid day sun in order to minimize further aggravation of the small moles on your skin so that they do not grow wild due to further sun damage.