Doctors misdiagnosed me for 13 years. My neurologist finally found what I had and brought me back to life.

• For 13 years, I tried to get a diagnosis for my symptoms of fatigue and trouble walking.
• Through an MRI, a neurologist discovered I have multiple sclerosis.

I glanced over the doctor's shoulder as he pointed to white spots on an MRI of my brain. "These are areas of demyelination." He spoke definitively, as if 13 years of no diagnosis for symptoms like debilitating fatigue, mobility issues, and pain, was just a big misunderstanding.

"Your spinal fluid showed evidence of inflammation. What we're dealing with here is multiple sclerosis," he said. His words filled my brain like carbonation from a soda, fizzing through my mind and stifling my thoughts. The idea that one simple test provided the answer I'd lacked for 13 years seemed like a dream.

I had tried everything up to that point

My search for a diagnosis had taken me to doctors as far away as a four-hour plane ride from my home. The futile suggestions had ranged from exercise to psychotherapy to a mixed drink, as if Smirnoff with a splash of cranberry juice could stop my body from declining.

When I reached the 10-year mark, I thought I'd dangle from the edge of the undiagnosed mountain for the remainder of my existence. But here I was in this exam room on a day unlike any other. It was a day I never thought would arrive.

He threw a list of medications in front of me as if it were as simple as choosing an item from a menu. There were pills, injections, infusions, and long lists of adverse reactions and possible side effects. I felt overwhelming relief with a side of fear.

"Will I walk normally again? Can these lesions heal? Are my legs going to fatigue this easily forever?" I stacked the questions one upon the other until they reached the ceiling. I'd waited for a diagnosis for so long, but I hadn't prepared myself to accept one.

I thought of the time I'd endured an unnecessary breast exam because the doctor demanded it. I remembered the time a physician told me there was no answer to be had as my body continued to decline until merely existing was a struggle. Today was a good day. An answer meant a treatment, and I deserved that more than anything.

I started feeling like myself again

I returned to his office many times in the coming years for checkups and to be infused with a B-cell-depleting medication to calm my disease. Just as years had passed during my search for a diagnosis, time came and went during my early years as a patient with MS. Slowly, my body showed a resemblance to what it once was. Gradually, my flares settled, and my abilities evened out over time. I could finally recognize myself again.

Then, earlier this year, this gentle, intelligent doctor announced his retirement. The stability I'd gained through my relationship with him crumpled beneath me.

I suddenly felt lost again, like I had during my undiagnosed years. He had given me all that I hoped for. This man had enabled me to have a second chance at life, and now I had to learn to walk this path without him. I wasn't sure how to.

Six months have passed since my doctor's retirement. I think of him every day. I recall his kind nature and his ability to think outside the box. I acknowledge my appreciation that the universe connected me to him and allowed him to guide me through the start of my MS journey. On the day of my last infusion in his office, I handed him a letter thanking him for saving my life. Without him, I'd surely still be undiagnosed, incapable of walking, and with no stamina to go on. Without him, my boys wouldn't have a mother.

Not many people can say their lives exist because of one good human. I can. And I will never forget it.

Lindsay J. Karp is a freelance writer and mother residing in the suburbs of Philadelphia with her husband and two sons. As an advocate for patients with multiple sclerosis, Lindsay shares her stories of life with MS and her struggle to receive a diagnosis.