The left side of my body spasms briefly upon walking or running, especially after rising from sitting position. been happening for a few years now.

Maybe PKD?: Paroxysmal kinesigenic dyskinesia (pkd) is characterized by unilateral or bilateral involuntary movements precipitated by other sudden movements such as standing up from a sitting position, being startled, or changes in velocity; attacks include combinations of dystonia, choreoathetosis, and ballism, are sometimes preceded by an aura, and do not involve loss of consciousness. Please see your neur.