Ryan Sutter reveals details of his mysterious, undiagnosed illness

Colorado firefighter Ryan Sutter, who won the inaugural season of "The Bachelorette" in 2003 and remains married to its star, Trista Rehn Sutter, has detailed the mysterious, undiagnosed illness that his wife last week said has plagued him for months.

Writing on Instagram Tuesday, the 46-year-old Ryan Sutter recalled that in February he transitioned from the Vail Fire Department to that of Denver. Toward the end of his 18-week fire-academy training there, "I felt more and more worn out and began feeling occasional 'flu like' symptoms. I was tested for COVID multiple times but never tested positive. I completed the academy and believed/hoped I would begin to recover and feel better."

Months later, however, "I feel worse. Though I am functional and continue to work my regular fire schedule, I am experiencing a battery of symptoms which include: fatigue — sometimes almost paralyzing, deep body and muscle aches, fevers, night sweats, full body itching with no rash, headaches, neck and throat swelling, congestion, light headedness, nausea, and just general all around not feeling good."

Despite "several blood tests and a CT scan," he wrote, doctors have been unable to determine a cause. He believes he is not contagious, "as no one else in my family has been sick nor has anyone I have worked with or associated with been sick."

"The struggle to find answers in the medical world and support through the insurance industry is frustrating and lacking," Sutter said in the second of three Instagram posts. "One must truly and persistently advocate for himself/herself if they hope to find answers or, at the very least, rule out possibilities."

Despite his health's uncertainty, Sutter in his final post urged the public, "Please don't worry about me. I will be fine. … The outpouring of support I have received has been humbling and therapeutic. I could not be more grateful."

The Sutters are the parents of son Max, 13, and daughter Blakesley, 11.