It's been five years since Canadian pop star Avril Lavigne has put out any music, but the wait will soon come to an end. Today, in an open letter to fans, the Napanee, Ont., native has announced that her new single, "Head Above Water," will come out on Sept. 19.

In addition to that, Lavigne discussed her battle with Lyme disease, an illness that's spread by ticks and, at its worst, can affect one's ability to move, cause joint pain, headaches, fevers or heart palpitations. "Those were the worst years of my life as I went through both physical and emotional battles," Lavigne wrote. "I was able to turn that fight into music I'm really proud of. I wrote songs in my bed and on the couch and recorded there mostly as well."

Lavigne says "Head Above Water" was the first song she wrote in bed "during one of the scariest moments of my life," she describes. "I had accepted death and could feel my body shutting down." She likens the experience to drowning or being pulled under a current.

She also noted that she will be starting a foundation to help raise awareness of the disease and help people with prevention resources. "I'm taking my life into my own hands and doing what it is I know I am meant to be doing in this life time," she continues. "Making music. And sharing my healing and hope, through my music."

Read Lavigne's full letter on her website. Her last album was 2013's Avril Lavigne, which featured collaborations with Marilyn Manson and her then-husband Chad Kroeger.

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