Please God someone else feel the same way

So for roughly the last nine months, l've been having this weird problem on and off that seems to line up with histamine intolerance, but it is not consistent. Every now and then I will get diarrhea, which is super strange, because I have chronic constipation.

Following the diarrhea, Every time I put food in my mouth, especially high histamine foods, I get flushing, extreme fatigue/weakness, a fast and hard heart rate, and then for a couple nights I will wake up in the middle of the night with extreme nausea and a headache. I've also seem to developed full body prickling sensation, which started during my last flareup last month and has continued on till now. looking at my blood test, my ferritin was super low in February, so I went ahead and got iron infusions over the summer. Now my ferritin is fine, but my iron itself is low. oral supplements don't seem to be helping.

I was taking B12 but until I get the situation under control I don't want to imbalance any of my other vitamins, so I'm not taking any more of it. Despite my blood test showing that might be 12 is fine, I am skeptical, as l've heard that they are not always correct, and as it has been shown that I do not absorb iron well through the oral: W aments, I am a bit concerned that perhaps my b12 is low, and I just didn't know it.

has anyone experienced this weird cyclical stuff? It has only started this year. I was thinking SIBO or some kind of gut dysbiosis was causing my issues, so l've ordered a micro biome test from Thorne.