Thanks all for your input. And thank you joegrane for such an indepth response. It's really useful to hear other people's experiences, and great to know that there is hope. I will take time to go through those links and learn what I can.
Currently looking at heavy metal, thyroid and adrenal issues with a nutritionist's guidance, who suspected thyroid and adrenal problems from the outset. Hair Mineral Analysis just back and showed no real signs of heavy metals, although Beryllium was high but nothing too much.
However, nearly all minerals (both nutrient minerals and additional minerals) were barely in reference range, except zinc which was too high. Toxic ratios suggest that Mercury is massively interfering with Iron uptake, as is Lead but to a lesser extent. I don't have any Amalgam fillings (no fillings at all infact) and as far as I'm aware have never been exposed to anywhere where mercury levels should be high. I've learned that heavy metals may not be appearing on the analysis as I haven't been 'unsettling' them - maybe it's time to detox/get them moving and have a retest to see if there's any change. Anyway, something to explore further perhaps.
I tried 12% LugolsIodine externally about a month ago and got what seemed like a herx reaction after 3 days - bags of energy, but much worse brain fog, headaches, hot and cold flushes etc. I found it surprising as only applied externally though. Stopped applying after the reaction. I wasn't supplementing with selenium but again maybe something to look into again.
Symptoms very much the same since original post, except added thinning of hair to the list of woes!
Thanks again for your help - it really is appreciated. Will keep you posted if and when I find the right path.