Lavigne's husband, Nickelback frontman Chad Kroeger, also used to pay her regular visits during breaks from the band's tour.
She said: "There were definitely times I couldn't shower for a full week because I could barely stand.
"It felt like having all your life sucked out of you."
Lavigne realised there was something seriously wrong when she just wanted to stay in bed instead of going out partying in Las Vegas last October, where she and some pals were to celebrate her 30th birthday.
She added to People magazine: "I could barely eat, and when we went to the pool, I had to leave and go lie in bed. My friends asked, 'What's wrong?' I didn't know."
While the star admits she is only "80 per cent better" at the moment, she is determined to get on with her life and paid tribute to her fans for helping her through her recovery.
She said: "They were asking about me since I was MIA, so I mentioned to one fan directly that I wasn't feeling good.
"The get-well messages and videos they sent touched me so deeply."
- Bang! Showbiz