Stomach fullness

I’m down to 7 foods, but my stomach reacts badly to the two most calorically dense ones (olive oil and chicken). I can’t get enough calories before I get stomach fullness/nausea/discomfort. And if I try to push past it, I throw up. I know it’s a symptom of mcas, because when I’m in a flare it gets worse and I can barely eat at all. I am losing about 1kg a week. At this rate, in a few weeks I will be underweight. I tried Kate farms and versions thereof. I am on cromolyn, quercetin, luteolin, Zyrtec, Pepcid. On ramping ketotifen, currently 0.2mg. I have xolair scheduled for next week. Is there anything else I can do to not starve? Would seeing a GI specialist help? Is there such a thing as medical nutrition without allergens maybe?