Christina Applegate has shared that she has been misdiagnosed with multiple sclerosis.

Applegate, 54, was diagnosed in 2021 with the incurable autoimmune disease that affects the brain and spinal cord, and has spoken openly about the debilitating pain of the condition. She revealed the health update Tuesday on her MeSsy podcast, returning after a seven-month hiatus due to health issues.

Citing new technology that contributed to the finding, Applegate said: “This may come as great news, but to me, I’m back at square one.

“It’s hard to say that [my doctor] came into my room and she said, ‘Congratulations, you don’t have MS.’”

The Married… with Children actor said she was “not happy at all” to hear the news.

“You don’t get misdiagnosed and then all of the sudden I’m better. I haven’t gotten better … If anything, I’ve gotten worse in some ways,” she said. “So I’m back at square one, that I don’t know what’s going on with me.”

After announcing her diagnosis in 2021, Applegate retired from acting in 2022 following the finale of the hit Netflix drama series Dead to Me.

Now, she said, her illness is a mystery. “I have every symptom of someone with MS. Every single one,” she said. “Now, we both know that there are many things that mirror MS — many different things.”

Applegate added that “there’s a pretty damn high number of misdiagnoses with MS,” so this is not a rare occurrence.

“It’s clear now that they’re finding something different,” Applegate continued. “Something else is going on.”

Expanding on her feelings, Applegate said she’s in a “state of shock.”

“It’s a mindf***, for sure. It’s this weird feeling because I became this — you and I, the poster children for MS,” she said to her podcast co-host Jamie-Lynn Sigler, who has MS. “I had a reason. I had a f***ing reason as to why my day sucked every day. And now I don’t have a reason and it’s very unnerving and it’s really confusing for me.

“I’ve gone through a great depression because of it,” she continued. “But I lost everything. I lost my job … It stopped my life. I still have to use wheelchairs when I go to the doctor’s office. I can’t walk from the car to the room. I’m still in this. Nothing magical happened when she said, ‘You don’t have MS.’ Nothing magical happened.”

Speaking earlier this year ahead of the release of her memoir, You With The Sad Eyes, Applegate told People she spends a big part of each day in her bed because her chronic pain makes it hard to move around.

Applegate said despite the excruciating discomfort, she is committed to her routine of taking her 15-year-old daughter, Sadie, to school and activities.

“I want to take her; it’s my favorite thing to do. It’s the only time we have together by ourselves,” Applegate told the outlet. “I tell myself, ‘Just get her there safely and get home so you can get back into bed.’ And that’s what I do.”