I also have high histamine in my body. Had 18” of my colon removed in April of 2022 for severe diverticulitis and since then have been diagnosed with Hashimoto’s/Hypothyroidism in November of 2022. Taking 112 of Synthroid and 5 of Cytomel. I also break out in itchy hives and had an allergist do a food sensitivity test on me and to my surprise, I am allergic to many foods. I’ve been staying away from these foods and do feel better. The first 3 foods you can eliminate are gluten, dairy and soy. I would try doing that and see if you notice a difference in your hives and the way you feel. I’m sorry you’ve suffered for so long, but I’m hoping those 3 food eliminations will help you. I would also have my Thyroid checked. You can have a blood test done and have your TSH, T3 Free, T4 Free and your thyroid antibodies tested for hypo or hyperthyroidism. I hope this helps and you feel better soon!