My wife stays tired all the time. About 10 minutes of moving around in the house requires her to rest beaseof rapid heart rate. Recent (this week) Heart PET scan showed abnormalities but heart cath showed no blockages or misfunctions. She is 100# overweight, is on thyroid meds, BP meds, Pristique, has one stent, had breast cancer 13 years ago. Bloood work showed low potassium and magnesium levels. Wat are possible causes of her fatigue, low energy level and rapid heart rate. She also has ulcerative colitis