Hi jmhilde, and a warm welcome
Hypersensitive is me written all over, and as you can read in my blog.
And yes: my CoV-jab reactions pointed me via the CFS/fibro site healthrising to MCAS. This at last also explained all my 100s of previous strong hyper-sensitivities / intolerances and helped me find supps etc. to curb the ongoing symptoms from the 3 jabs.
My hypersensitivity is in quite a different dimension to yours though:
I had a “pixie dust” phenomenon with melatonin (even 5% of a 2mg tablet zombified me), T4 (3% of a 25µg tablet is enough for major improvements in energy, but also 2 downsides) and now with CoV itself: My wife has it and is testing positive. I have much worse symptoms, but am testing negative.
Looking more closely at your med amounts, both aren’t low at all, they’re normal, as are your reactions!
100mg of elemental magnesium per each of 3 meals would be a normal dose, not a tiny dose. The max. recommended dose is 300mg/d (more for men, less for women). 500mg is way beyond that, and most people would get diarrhea from that, so I’m surprised your neurologist team even thought about it, esp. if that was for fibro, because a third of us have IBS and many of these IBS-D - it’s a pretty dangerous suggestion in my opinion. (Most vitamins are harmless when hyper-dosed, but minerals are definitely not.) Unless they meant the amount of the compound, not the element. That however would be underdosing, cos a 500mg pill of magnesium glycinate contains only 50mg of elemental magnesium (a bit above 10%).
My main idea here is to try other forms like malate or threonate. The malate form is a combination with malic acid, whilst glycine is an amino acid / neurotransmitter.
And more importantly, you did not underdose at all, that was a normal maximum dose. So you could try less. But I wouldn’t touch it any more (either), I’d go for other types, dose halved, and/or for high doses of the B-vitamins.
Similarly gabapentin: 300mg is exactly the dose recommended for hot flashes in this 2013 study: Comparison of Gabapentin with Estrogen for treatment of hot flashes in post-menopausal women - PMC confirmed here in 2020 Gabapentin for the treatment of hot flushes in menopause: a meta-analysis - PubMed
Also it’s normal for us people to react badly to gabapentin/Neurontin at any dose, same as any med. That can be “explained” by fibro.
Does that help?