Please do check into the thyroid problem. Also, check out Mary Shomon on About.com. Sometimes thyroid problems don't show up upon initial testing. I have hypothyroidism, and let me tell you, it's tough! I've lost 99 pounds, but it's been an uphill battle, clawing and scratching all the way. I've had weight loss plateaus that lasted 5 months, all while I was eating l200 calories a day in fresh fruits and vegetables, low carbs, and no meat (vegetarian). It's taken two years of dieting and a LOT of exercise, but if you do have a thyroid problem, don't give up. It's hard, but it's not hopeless.
Shari