emmie, just asking if you have been tested for coeliac disease because a lot of your symptoms sound similar, even the skin itching/rash (dermatitis herpetiformis). You seem to be going through terrible things there so just thought I'd throw some ideas into the ring. Maybe you have been tested though?
Here's some of the symptoms associated with coeliac disease and with it being a multi system disorder it can be really debilitating:
severe or occasional diarrhoea, excessive wind and/or constipation, persistent or unexplained gastrointestinal symptoms, such as nausea and vomiting, recurrent stomach pain, cramping or bloating any combination of iron, vitamin B12 or folic acid deficiency, anaemia, tiredness and/or headaches, sudden or unexpected weight loss (but not in all cases) mouth ulcers, hair loss (alopecia), skin rash, tooth enamel problems, depression, liver abnormalities, repeated miscarriages, joint and/or bone pain neurological (nerve) problems such as ataxia (poor muscle coordination) and neuropathy (numbness and tingling in the hands and feet), amenorrhoea (lack of periods in women