Hi there. I wish I knew more about your disease. Perhaps if you post on the auto-immune or heart disease forums someone there might know. You should really check with your doctor on the faintness.
For your health issues a low saturated fat and low cholesterol diet is needed. Eliminate butter & saturated margarines (replace with low cholesterol margarine and canola, olive and other vegetable oils), replace high fat meats with lean cuts, increase your chicken intake (no skin) and fish intake and fresh fruits and vegetables. Low fat dairy, legumes and whole grains are good to add to your diet. Reduce your intake of white carbs and sugar.
For exercise try looking into swimming which is easy on the body and can cool you down. I've found the food diary and weight tracker very valuable. Stick around and join in our weekly weigh in (Sundays). We're here to help and support you.