Randomly, about once a month, i'll start sneezing and then keep sneezing for about 10-12 times? Why?

Allergen or irritant. Sneezing is an involuntary reflex response that occurs when your nose encounters something it doesn't like - usually something you're allergic to, or something that's simply irritating to the nasal membranes. When it happens, be aware of where you are and what's happening around you. You may be able to identify the source and avoid it.