Right Arm and Leg Numbness/Weakness

I'm hoping someone will post an answer to this very frustrating problem. My Mother is 70 years old and for the last three months has had morning bouts of numbness/weakness in her right arm and leg. She says it feels like her arm and leg are numb and shaking. The shaking is not visible to me, she can only feel it. She has been hospitalized twice for this and they can't figure it out. She has been to a neurologist and he has done, MRA, MRI, CATScan, EEG, EKG and they are all normal. She is only Levoxyl for her thyroid, BP medications and Gabapentin for the nerves. The Gabapentin is helping but the numbness is still there and it's very irritating for her. She is not able to drive anymore because she doesn't know when the leg is going to go numb on her. Other medications she is on are,

Levothyroxine   .112 MG               Thyroid                (once a day)

Simvastatin         40 MG                   Cholesterol         (once a day)

Hydrochorathazide         12.5MG                BP           (once a day)

Amlodipine                         10MG                    BP           (once a day)

Conidine                              .1 MG                    BP           (twice a day)

Metformin                          500 MG                Diabetes              (once a day)

Benazepril                           20MG                    BP           (once a day)

Arimidex                              1MG                      Cancer  (once a day)

Omeprazole                       40MG                    Stomach              (once a day)

Neurontin                           300MG                 Nerves (2 @ bedtime and 2 during day)

Does anyone have these same symptoms and can shed some light on this for us???

Thanks

Kathy