Oral cromolyn sodium is a mast cell stabilizer. It's used for people with mastocytosis and food allergies.
I have food reactions of a pretty typical sort - characterized by a groggy (dazed, mentally impaired) state that starts coming on about 1/2 hr after eating the food and comes on fully 4-5 hrs after eating and lasts about 4 days; other symptoms may include physical clumsiness; diarrhea (usually I don't get diarrhea); itching; frequent urination; and psychological effects like irritability, emotional hyper-reactiveness, tension.
I wanted to be able to take Singulair for my inhalant allergies. Singulair helps with the late-phase aspects of allergic reactions - it decreases the fuzzy-headed, difficulty thinking, foggy, low energy state. But I had a hard time finding Singulair from a compounding pharmacy - I do have a food reaction after Singulair tablets from a regular pharmacy.
So I started cromolyn. It's something you take 4 times/day before meals, the effects build up over 2-3 weeks.
I found that if I took cromolyn before the Singulair tablet, the food reaction was much decreased.
Since cromolyn is a mast cell stabilizer, this suggests that my food reactions involve mast cells.
The usual dose of cromolyn is 200 mg 4x/day, and one can increase it to 400 mg 4x/day.
Cromolyn usually comes as Gastrocrom, and it's hugely expensive. But, I was able to obtain it in powder form from a compounding pharmacy and they only charged me $129 for 120 200 mg capsules. The pharmacy I used was America's Compounding Center, apparently they use a supplier that was able to get this drug inexpensively. Another compounding pharmacy wanted a much higher price for it.
So you might be able to liberalize your diet for $129 per month - or maybe, twice that at the higher dose of cromolyn.
If you want to try cromolyn without a prescription to see if it works, you can take it as Nasalcrom, which is over the counter. Nasalcrom is the nasal spray version of cromolyn, it's a liquid. Nasalcrom does contain benzalkonium chloride and edetate disodium as preservatives, so it might not be a good idea long term - the dose for oral use is much higher than the dose used as a nasal spray. Possibly the preservatives might disturb one's gut microbial ecosystem, so taking Nasalcrom orally may not be a good idea long-term. But I used Nasalcrom to minimize the allergic reaction to the Singulair tablets, before I got a prescription for oral cromolyn, and I didn't notice any bad effects.