So sorry to hear you are going through this!   What OTC med did you take?  

Yep,yep,yep, called it from experience.  I've lived through SIBO and Candida myself.  I get a different sorts of reactions to dairy, high sugar consumption, and gluten.  I react to Casein, the protein in dairy.   Try the AIP diet.  Dr. Sarah Ballantyne designed it and is a Celiac herself.  Her book, the Paleo Approach, has been most helpful.

Yes, I know.   Without sufficient Folate, Cobalamine, and Pyridoxine, the body can't get rid of high homocysteine levels.  High homocysteine levels make one restless, interferes with sleep and resembles ADHD symptoms.  High homocysteine levels occur in Celiac Disease.  Chronic high histamine levels lead to high homocysteine levels. Impact of supplementation with vitamins B6 , B12 , and/or folic acid on the reduction of homocysteine levels in patients with mild cognitive impairment: A systematic review https://pubmed.ncbi.nlm.nih.gov/34058062/ Homocysteine, Pyridoxine, Folate and Vitamin B12 Levels in Children with Attention Deficit Hyperactivity Disorder https://pubmed.ncbi.nlm.nih.gov/30267523/ Simplifying the B Complex: How Vitamins B6 and B9 Modulate One Carbon Metabolism in Cancer and Beyond https://pmc.ncbi.nlm.nih.gov/articles/PMC9609401/ Prevalence of hyperhomocysteinemia in adult gluten-sensitive enteropathy at diagnosis: role of B12, folate, and genetics https://pubmed.ncbi.nlm.nih.gov/15952099/ Homocysteine, Vitamins B6 and Folic Acid in Experimental Models of Myocardial Infarction and Heart Failure-How Strong Is That Link? https://pubmed.ncbi.nlm.nih.gov/35454125/

You called it @knitty kitty.  I went to another health care provider for another opinion, and based on some tests they did, they suggested I might also be dealing with a fungal issue (candida and/or mold).  I saw that you mentioned before in this chain that some people on this forum also get Candida infections.  So it seems that I am possibly dealing that issue in my gut as well. I think some of the symptoms that I've been not able to understand now make a lot of sense within this context (such as why eating dairy and sugar sometimes causes me to get headaches, joint pain, chills, feel like I have the flu... if these things are making the candida infection worse by feeding the candida, and then my body responds by trying to fight it off, then I basically am fighting off an infection, which is exactly what it feels like).  The flu-like reaction that I get when I eat dairy is a distinct reaction than the one I get from getting glutened (which is also bad, but different: headache, sharp abdominal pains, gas, diarrhea). That's what made me think there was something else at play. 

I'm concerned about calcium.  I don't think I'm getting enough especially since I ended up having to get off dairy when I went gluten free.  However, if you have too much calcium, it can deposit in the wrong places and you can get thinks like bone spurs.  I'd like find a decent supplement for that.  Was thinking of looking into the algae based calcium supplements since they're more natural than some of the others available, but seem rather expensive.  When possible, I try supplement with food sources.  One or two Brazil nuts usually have the full RDA for selenium.  One Barbados cherry has the daily RDA for vitamin C.  I also use seaweed to help supplement iodine since I don't use iodized salt.