Hi Happeechic,
I've arrived here at this forum because of histamine intolerance.
Something I've found hugely helpful with the palpitations/arrhythmia and ectopic beats has been hawthorn (leaf and flower) tea. I alternate with Linden/Tilia flowers, but drank every morning for six weeks straight. Now just a couple of times a week. I'm also taking Ashwaghanda before bedtime. It's helped tremendously. I was suffering every night in the early hours and now only on a rare occasion.
I don't know if that can be helpful to you.
I also am a huge fan of nettles- tea, soup, pesto etc. If you harvest your own, just take the fresh tips (top 4-6) leaves, and only harvest young nettles. Not the right time of year now... Well- not where I live.
Obviously, lowering histamine using diet and boosting B12, Zinc, L-glutamine, DAO(I eat pea sprouts),quercetin, vitamin C, omega 3's etc.
I hope this info might be of some use to you 🙏✨️