I have very thin hair, acne, I m very skinny despite trying very hard to gain weight, and my heart always feels like it s pounding out of my chest. I get short of breath often when speaking. I used to consider this symptoms of smoking, but I no longer smoke. I ve started jogging and drinking more water to improve my health, but still have sick spells that leave me feeling light headed and I m tired all the time. I have no energy for anything, and getting exercise is a chore to make myself do. I m beginning to think that there may be something wrong. What could it be?