Numbness from the waist to the left leg?

Disconcerting: This is not to be taken lightly, and needs to be evaluated asap. You are describing a sign of spinal cord dysfnctn, which could be due to a host of disorders. Consider, a possible spinal cord avm, a tumor, multiple sclerosis, vasculitiis, even vitamin overdose toxicity (b-6). Get MRI images of thoracic spinal cord, see a neurologist or neurosurgeon.