DOUBLE OUCH!!!!! Oh my.

My heart and soul are with you? It’s bad enuf to get even ONE diagnosis? But two??? They are treated differently tho, I believe, and do give the IVIG a try to see if it helps one part of the ‘problem’. Golly I almost wish that your husband had been there? But at the same time, maybe not. You have to take time to process this all, and then find the best sources to give him [doc included] to help HIM asorb it all.
At least, on the good side? You weren’t ‘imagining it all’!!!! Be sure to ask this doctor for some diagnosis in writing? Just so you have it in hand for the future. Paper CAN be important at times. Or, useful at others.
Keep faith in yourself, and learn as much as you can and then? Start tilting at the windmills! Keep dreaming and hoping. For me those two things give me the patience I need to get on. I hope it helps you too!