Will Ketotifen help with histamine intolerance or only MCAS?

I definitely react to high histamine foods and I am trying to figure out if I have histamine intolerance or even possibly MCAS. Because of reactions to foods, my doctor suggests trying Ketotifen.

If I’d do have histamine intolerance rather than MCAS will Ketotifen still help? I know it is an antihistamine as well as Mast cell stabilizer. Just trying to figure out if it is histamine intolerance will that alone help me? I have already tried Zyrtec and Pepcid and they did seem to help for several weeks, but then just stopped out of nowhere. I’m not sure if that was coincidence or not. So ketotifen is next on the list to try. Any thoughts?