Christina Applegate Says Breast Implant May Have Caused MS-Like Symptoms

Christina Applegate says there's a chance her breast implants resulted in her being misdiagnosed with multiple sclerosis ... saying they're long overdue for replacement -- and could be leaking in her body.

The actress dove into her not-so-funbags on an episode of her "MeSsy" podcast with Jamie-Lynn Sigler ... and said a loved one recently sent her research which suggests a leaking breast implant can poison one's body and be misdiagnosed as MS.

Christina says she had a double mastectomy in 2008 ... and she never went back to have the implants replaced.

While she might not have MS, Christina points out she's in a tremendous amount of pain ... saying she can't move her arms or shoulder -- and still has trouble just getting out of bed.

As we reported ... Christina told her fans that she doesn't have MS -- and she's undergone more tests to determine exactly what she has.

The misdiagnosis isn't exactly a relief for Christina ... who says she's frustrated because she has no clear answer about what's wrong with her.