As Homeagain suggested, you might be sensitive to IgA and IgM in the IVIg. Consider asking you doctor to switch brands. You might also be sensitive to the rate at which you were infused. A slower rate would be a good idea. It is a good idea to be very well hydrated before, during, and after the infusion. Try to drink a half gallon of water for a couple of days before, the day of, and the day after your infusion. My infusion center automatically gives Tylenol and Benadryl (or the generic equivalents) before IVIg (unless they are contraindicated for the patient).
I use plasmapheresis as one of my main treatments. What happens is your blood is sent into an elaborate centrifuge system, where the plasma (the liquid) is separated from the red and white blood cells. The plasma is diverted to a waste collection bag and the cells are mixed with human albumin solution and sent back to you. The thought is that by reducing the number of bad things (cytokines and antibodies) in your blood stream, you slow down or stop the attack on your nerves.
You can have plasmapheresis with two venipunctures, one in each arm. You will need large veins, though, because the needles are necessarily large diameter. If you don’t have large veins, a catheter would be necessary. At first, you would get a temporary catheter. It is unpleasant to get (minor surgery, done with lidocaine), and a nuisance while you have it, but it is definitely worth it to find out if plasmapheresis will work. If it does, then you would most likely opt for a more permanent one.
As for a new neurologist, Weill-Cornell has a well-regarded neuromuscular program. You might try them.
Godspeed in finding a tolerable treatment,