I know We Are All Different etc, but re B12 deficiency I will give a slight warning based on my own experiences. Severe B12 deficiency can do very bad things to you - especially nerve damage (as I know to my cost). But once it's recognised and being treated it is not a problem. If you are on injections it is easy to convince yourself that you are feeling exhausted because your 3-month injection is due so you must be running on empty but this is not the case - you will still be well in the safe zone. If they only have you on tablets then your B12 deficiency is not too severe. I write this not to sound unsympathetic, but to warn you that if you are really suffering from tiredness, dizziness, breathlessness it is really important not to let HCPs brush it off by telling you that it is just your B12 deficiency -- it is very likely to be something else (blocked coronary arteries in my case) and it is important to get it checked out.