Christina Applegate is "back at square one" after learning she was misdiagnosed with multiple sclerosis.

The Dead to Me star, 54, shared a shocking health update with fans on the October 20 episode of her MeSsy podcast with Jamie Lynn Sigler, revealing that she was recently told by her doctor that she doesn't have MS, five years after her initial diagnosis, per E! News.

"She came into my room and said, 'Congratulations, you don't have MS,'" she recalled. "I was, like, not happy and all. Everybody else was so happy."

While she acknowledged that some people may see the revelation "as great news," Applegate got emotional as she explained how she feels like she has taken a several steps back in her health journey. Despite learning she doesn't have MS, she still suffers from debilitating and painful symptoms; only now, she doesn't have a diagnosis to tell her what is wrong.

"You don't get misdiagnosed and then all of the sudden I'm better. I haven't gotten better, Jamie! If anything, I've gotten worse in some ways. So I'm back at square one, that I don't know what's going on with me," she said, adding, "I have every symptom of someone with MS. Every single one. Now, we both know that there are many things that mirror MS — many different things."

In the second episode of the two-part conversation, emotions continued to run high as the Anchorman actress described the impact of her health battle over the past several years, People reports.

"I've gone through a great depression because of it. But I lost everything. I lost my job. I lost — I'm sorry. What do you say to someone who's been living with this for six years — God, I'm so sorry — because it stopped my life," she said. "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."

Applegate said she's still in a "state of shock" over the misdiagnosis, calling it a "mindf---," and that she is also grappling with how it impacts her place in the community she has built with others struggling with MS.

"It's weird because I feel like I let everybody down," she said. "It's this weird feeling because I became this — you and I, the poster children for MS. And everything I was doing. 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 very confusing for me."

AJ