The source went on to claim that the Canadian singer has "gone through hell" over the past 12 months as she battles the rare disease, which causes agonising pain and debilitating muscle spasms.
Dion did start making public appearances in recent weeks.
The 'All By Myself' songstress made her first appearance in three-and-a-half years when attending an NHL game on October 30 night between the Vegas Golden Knights and her hometown team, the Montreal Canadiens.
She reportedly managed to sing "a few notes" during the outing.
Later, Dion showed up at Katy Perry's final Las Vegas residency show "Katy Perry: PLAY" on November 4.
A clip from the show saw Celine dancing and bobbing to the music.