Hi I am a 21 year old Caucasian female, about 5 7 and a 1/2 and weigh 8st 8lbs. I have been this weight consistently for about a year now after losing weight slowly and healthily. Prior to this I was no more than a stone heavier but I have not had a period in over two years. I do not smoke , consume caffeine, alcohol or eat any meat except occasionally fish, as well as always making sure that my meals are well balanced. I also make sure I walk for at least half an hour minimum every day (often more) and go running about three days a week for about 1 mile to 2 miles. I have had numerous blood tests in the past year for various things (such as hormones and electrolytes) that have all returned normal results; had a smear test which was clear; my ovaries examined and confirmed to be fine. Recently however, I had been regularly finding myself dizzy, light-headed and faint whilst sitting or standing; short of breath as if I am unable to breathe in deeply enough and occasionally getting odd palpitations. I have a very slow pulse (about 54bpm even several hours after lots of cardio exercise), very low blood pressure and easily feel the cold. Occasionally I have had chest pain (sometimes while running), however after seeing a cardiologist and having my heart examined on a monitor, it would appear to be functioning healthily. I thought it could be either an electrolyte balance or pernicious anaemia but my tests appear normal and I make sure I consume enough iron and iron-absorbing foods containing vitamin C . The weirdest thing that has happened to me recently was one night when I spent several hours unable to sleep because I couldn t get enough air into my lungs. I sat up in bed dizzy and with a headache, while my chest was palpitating, getting a fuzzy pins and needles feeling in my hands and feet and knees; then I felt a persistent buzzing noise flood my ears and couldn t hear properly, but then it went away after a few minutes. After several more hours of trying to sleep I kept feeling as if I would lose consciousness . However, when I awoke in the morning, it was only really my respiratory difficulty that remained. These symptoms have improved in the last fortnight and my breathing is slightly better now, however my amenorrhoea is still a big worry. My family complain I am too thin which I dispute because my BMI remains in the healthy range. Overall, I think I am a very healthy and happy individual otherwise and am therefore slightly concerned that I should be experiencing such peculiar symptoms. Any advice would greatly be appreciated.