Thanks! Yes, I gather the low zinc/ low stomach acid can be a bit of a vicious circle. I'm supplementing zinc piccolinate to try to restore things. I do wonder about the fight/flight thing as despite not being actively stressed and doing regular relaxation stuff I do feel like my body is 'braced' for no obvious reason and thought it was bad habits. I'm going to try to learn Alexander Technique for re-learning muscle relaxation; can't say I'm aware of kinesiology but that's more food for thought! I don't drink caffeine or fizzy drinks so I get through lots of herbal tea at work but should probably get more water instead!
Thanks again everyone for all the advice and help - very much appreciated!