“What would cause pain on the entire left side of the body?”

How come nothing on the left is excluded and nothing on the right is included? Just like the body is cut in half. This started one year ago this month with a prickling and numbing sensation. It moved to pain and the pain has been increasing. I take Gabapentin 4 times a day, it takes the edge off but does not stop the pain. The doctor has no idea of the cause but believes it has something to do with nerves. An MRA and MRI of the brain did not show why. The patient is a 57 year old male who takes several medications for various health issues including diabetes, high blood pressure, and high cholesterol. I am hoping the doctors have access to a medical website that will allow for consultation. The symptom of the entire left side is so specific, that if anyone has ever heard of this, they would remember.