"I'm not feeling well," wrote the Napanee, Ont., native Sunday in a direct message to @AvrilMusicChart, a Lavigne Twitter fan account."I'm having some health issues. So please keep me in your prayers."
The fan, @AvrilMusicChart, shared the exchange publicly on Tuesday.
"I feel bad because I haven't been able to say anything to the fans to let them no why I've been absent," said the note. "I'm torn as I'm quite private."
A representative from Lavigne's label, Sony Music Entertainment Canada, wouldn't comment to CBC on the singer's health. But a rep for Lavigne confirmed to Billboard magazine Tuesday that the Twitter exchange posted by @AvrilMusicChart was authentic.
The singer's specific health problem wasn't described, but Billboard confirmed that Lavigne is not pregnant, as has been speculated.
Fans are tweeting with the hashtags #GetWellSoonAvril and #PrayForAvril to offer their support.
Lavigne lying low
The singer hasn't been photographed in public since her 30th birthday party in September.
The pop rocker rocketed to fame in 2002 with her breakout hit Complicated, but her most recent album release, Hello Kitty, was widely panned by critics, with Billboard calling the single's Japanese-themed video an "embarrassment in any language."
Lavigne’s official website hasn't been updated since April, and there are no upcoming events planned.
Lavigne has been married to Nickelback's Chad Kroeger since Canada Day 2013.