Lavigne, 30, took to Twitter to explain to her fans why she's been absent and hasn't been seen in weeks.
The singer interacted with a fan site @AvrilMusicChart and wrote in a direct message, "I feel bad because I haven't been able to say anything to the fans to let them (know) why I have been absent. I'm torn as I'm quite private. I'm not feeling well. I'm having some health issues. So please keep me in your prayers."
She did not specify what she's been dealing with.
Fans reacted in support tweeting the hashtags #PrayforAvril and #GetWellSoonAvril.
A rep for Lavigne had no comment about the illness.
Lavigne married fellow rocker and Nickelback's lead singer Chad Kroeger last summer and when she wasn't seen out with her husband in weeks, rumors of relationship woes started to circulate.
Over the weekend Lavigne thanked her fans for the support.