I'm very sorry that this is happening to you. The first thing I have to ask is is you have a family Dr who could refer you to a different neuro.
If it's the tremors, I think an opinion from another neuro is in line, hopefully you have a good general practitioner who can guide you.
I was on this kind of merry go round for 7 years, so I can most certainly relate to your feelings. Just rest, give yourself time to get over this blow, and start again.
I am not a Doctor, but I think some of what the Rheum is telling you is just about it. I had been put on an oral med that made me vomit uncontrollably, I couldn't even keep water down, and my Rheum told me that I had many more Meds to try, that might help with the joint damage for PsA, which is my primary autoimmune, but that some people just cannot take them, not everyone can tolerate them. I personally will try anything to keep me out of a wheel chair or nursing home. The immunosuppressants not only slow down the progression, but help the pain and fatigue.
I recently had to go off the Humira, I had a wicked flu that turned into bronchitis over night, what a disappointment that was, as the Humira was just starting to work.
I know there are people here that do not, will not, or cannot take Meds, but I encourage you to do your very best to give them a try. Sjogren's is systemic, eating smart is a good idea, but crash diets can be very stressful, so please take care there. If you are determined, please consult a nutritionist to be sure you are getting what your body needs to function.
I know there are others here who may disagree, but unless you have a food allergy, why go through an extreme change in diet. Try to stay away from preservatives, additives, and buy cold pressed expeller oils for cooking and baking. Eat organic when you can. The health food stores are full of organic nuts, and fruits, whole grain products. It never hurts to eat smart, but it will not get rid of autoimmune. My Rheum insists it's genetic, he practices and teaches.
Just don't give up! There is a doctor out there for you. If you have to, go to the biggest University hospital you can get to to address the tremors, and talk to a another Rheumatologist.
Hang in there, girlfriend. Don't give up!
Wishing you well,