Will my histamine intolerance improve if I fix my SIBO?

I've never had these issues before but it's becoming debilitating and unbearable. It was good for the month I was on an antihistamine for my sinuses but as soon as I stopped symptoms came back with a vengeance. My heart pounds so hard for hours after almost every meal, my chest feels like there's an anvil in it and my stress meter (HRV) hits the max level. My blood eosinophils have never been higher even while on antihistamines so I'm guessing that means my intolerance is getting worse. From a quick google some articles say there isn't really much you can do about histamine intolerance other than the immensely restrictive diet.