What are possible causes of getting goosebumps on one leg. some times it happens several times in an hour while sometimes i will go a couple days with?

Goosebumps: Goose bumps are a temporary local change in the skin. The chain of events leading to this skin change starts with a stimulus such as cold or fear or heat stimulus causes a nerve discharge from an involuntary portion of the nervous system called the sympathetic nervous system. The nerve discharge causes contraction of little muscles called the arrectores pilorum (the hair erector muscles).