Hi ive been getting random patches of goosebumps on my leg almost daily for a few months. its only on my left but was at first on my right. ive been seeing a physical therapist and have piriformous syndrome, and think its related but am worried?

There are various causes of recurrent goose bumps in addition to feeling cold. When they occur on only one limb it may be a form of autonomic nervous system imbalance but, in the absence of other imbalance symptoms, I don't regard this as necessarily serious in your case such as can occur in some seizure disorders. If you still have concerns, consult a neurologist.