Sorry you had such a negative experience. Although the doctor was obviously insensitive (and even sounded arrogant), she made a couple valid points. IVIG is an extremely costly medicine that does carry considerable risk. As we have discussed here for many meds...there is the benefit vs risk assessment. You don't seem to get as much benefit as would be expected. One week of minimal pain reduction (not relief) is not worth the risk...IMO And you also report side-effects as well as continued other symptoms and disability. So is it really working?

You may have some autoimmune process (40% of Sjogren's patients have negative blood work for antibodies), but your blood work now can be altered from the IVIG, so any further testing (blood) is pointless...and even for up to 4-6 moths after stopping IVIG. The NIH rare disease clinic "may" not take your case until you've been off for months.

I certainly don't have any magical answers for you. I understand your search for answers and know all about wanting to try anything that may help. My only suggestion is to stop and look at whether the IVIG is really making enough of a difference for the risk involved. Is your quality of life better and pain significantly less by the IVIG? If the answer is no, then you need to re-evaluate the Rx.

If you have not had the EMG before, then I would do so. But it sounds like you've had a full work up already.