@bluesfan

Thank you for your encouragement and story.
Zinc: I had no real reason to take this as my diet contains a lot; I just did it due to advice about hypothyroidism. I thought I was cautious about taking supplements having only taken them when I actually identified a reason (rather than taking them ‘just in case’). However, since being here and learning more from my blood tests, supplements can have serious consequences sometimes so I will only take them based on evidence (i.e. blood tests and research).
Selenium: I stopped taking that too actually, since stopping the zinc. There’s quite a bit in my diet!

@mrsD

Thank you again for your input. The first link was one I had read before and made me ponder the possibility of having a gene mutation. If I can get it tested I will as soon as possible.
The second link I had not found despite scouring scientific journals for it! I have some great scientific literature about vitamin B6 and they all draw a similar conclusion: it’s undocumented (i.e. impossible at the moment) to develop B6 toxicity from food alone, which is my only source of B6. Although my diet is rich in B6 I discount it as a cause unless I find evidence to the contrary, which I suspect may not happen for some time. As you said, research on B6 tends to focus on deficiency rather than the few cases of megavitaminosis.

@Healthgirl

Thank you for the note about bacteria. I’ve no digestion problems but it could be an avenue to investigate if over the next few months I don’t get to the bottom of this. I now agree completely about being cautious with supplements! As for getting blood tests for what you suggested: unlikely to happen anytime soon. My current doctor (as mentioned previously) is really stubborn about blood tests and quite hard to predict. I am in the process of finding an easier avenue to get them done.

My hypothesis for good blood testing is just to do a whole bunch in one go. Then do a follow up a few months later, then I guess, annually, dismissing the minerals/vitamins that are at good levels. The way I get them now just seems like a waste of money and done almost at random (not my choice!)

Update

What I’ve done and am doing: Stopped zinc and selenium supplementation. Increased methylcobalamin consumption to 5microg per day on an empty stomach.

What I feel: Symptoms are still there but they are not worse. If anything I feel better which could be noticing the symptoms less often, feeling less anxious about it all since getting help here (thank you all again by the way), or the changes above. I am acutely aware of the power of hypervigilance on the body, so I always try to note symptoms when I feel my best and without too much thought.

My plan: Keep taking methylcobalamin at 5microg per day for about 1 month, stopping 3 days prior to a blood test (if I can get one), then recommence at 1microg per day until the results come out – then go from there. Additionally, I will try to test all the substances recommended in this thread, including a genetic test but that is at my doctor’s discretion (whom I hope to replace soon!)

Questions
I seem to have no adverse effects from methylcobalamin but I have one complaint: the sugar. I consume no refined sugar (not even honey) and I don’t like having sublingual pills that are full of sugar hanging around my mouth every morning! Does anyone know a good methylcobalamin pill without sugar? Taste is irrelevant, I don’t care about foul tasting medication! I noted your hypothesis mrsD about the molecule being too large to be absorbed via the tissue under the tongue and I am inclined to agree. This morning I just dissolved the pills in water then drank it, followed by more water to hopefully wash as much of the sugar away as possible.

This place has helped me feel so much better already and I appreciate the interest and sharing of knowledge. Sorry if I am over the top about it but I am sincerely grateful!