ATLANTA -- Millions of women feel sick and tired all the time, and their doctors just can’t seem to figure out what’s wrong. That’s a frustrating reality for millions of women who suffer from unexplained fatigue and weight gain.

Cindie Parmelee used to be one of them. She’s now a vivacious day trader and single mom of two, but she wasn’t always that way.

Cindie would trade anything to get back the years she lost when her health went haywire. It happened in her 30s, shortly after she gave birth to her first child.

“I kind of went in a downward spiral to where I felt half-dead,” Parmalee said. She was suddenly too tired to function, suffered chronic headaches, became depressed and gained weight.

“I think I probably wasted a good five years of my life being tired and lethargic, worn down, agitated and aggravated,” parmalee said.

After hitting rock bottom, Cindid turned to Dr. Karen Bullington for help. Dr. Bullington practices medicine at Fibromyalgia and Fatigue Centers in Marietta. After a series of blood tests, Dr. Bullington found the culprit was an underactive thyroid gland, also known as hypothyroidism. “10 to 12 million Amercians have already been diagnosed and are being treated for low thyroid,” said Dr. Bullington.

The gland is located at the base of the throat. Its job is to produce hormones that control your metabolism and other body systems. When it’s not working properly, it can crate several symptoms. The most common symptom is fatigue, but some people might have trouble concentrating or remembering things. They may also have more physical symptoms like dry skin, hair loss or heavy menstrual periods.

“You can have those same symptoms for other reasons, so that makes diagnosing and treating thyroid conditions somewhat confusing,” says Dr. Bullington.

In many cases, Dr. Bullington said, a simple blood test can detect a problem, but some may need more thorough testing. If you have any of the symptoms, you should talk to your doctor immediately.

Women who are pregnant are most at risk, followed by women over 50 and those with a family history of thyroid problems, doctors said. As for the treatment, one pill a day will do for most people, but the type of medication can vary from patient to patient.