AceShowbiz -

Kristen Johnston, who is popular for her role on "Third Rock From the Sun", is battling a rare autoimmune disorder. The Emmy-winning actress took to Facebook on Tuesday, December 17 to tell her fans about the disease and that she felt better after undergoing treatment.

"I've been really, really sick since early Sept. Full body muscle weakness to the extent that just walking difficult, stairs impossible and I even need a neck brace to hold my head up," she wrote. "Lying down I'm fine, which is great for writing or killing time on social media (thank you all!!), but it's kind of disastrous when you're in a sitcom that requires tons of physical comedy."

"This lucky lady spent 2 fun-filled weeks in November partying at The Mayo Clinic. Come on...Who's jealous?" Johnston added. "After 4 months & 17 Drs (no lie) I've FINALLY been diagnosed with a rare auto-immune disorder. Meaning my immune system has decided to go rogue & attack my muscles. The good news: I'm finally on the right treatment, feeling better & back at work!"

The star of "The Exes" later thanked people who kept supporting her when she was in recovery. "I gotta say, TV Land and everyone at 'The Exes' have been just amazing, all of them...so patient, understanding, loving & supportive. It's true that when you're sick, you find out who your real friends are," she wrote.