Spinal tap was negitive

We are seeing a Neurologist. Emg was pos. MRI Neg. CAT Neg. Blood work, some Neg some pos. He has no reflexes in his knees or feet. His left shoulder is dropping, he drags his feet. He falls all the time. Leg cramps, feet pain headaches and stomach are the biggest complaints now. The Neurologist is giving him IVIG every 6 wks. He gave this second one early because his symptoms came back so fast.