The 30-year-old singer broke down in tears as she revealed she was bedridden by the disease last October and frustrated as she saw specialist after specialist, each unable to properly diagnose her Lyme disease.
"They would pull up their computer and be like, 'Chronic fatigue syndrome.' Or, 'Why don't you try to get out of bed, Avril, and just go play the piano?' It's like, 'Are you depressed?'" she explained to "GMA" special contributor Jesse Palmer.
The singer added, "This is what they do to a lot of people who have Lyme disease. They don't have an answer for them so they tell them, like, 'You're crazy.'"
The "Complicated" singer told "GMA" she's now about halfway through her treatment and is doing "a lot better," and believes that she will make a full recovery.
Lavigne first opened up about her battle with Lyme disease in April in a People magazine cover story.
"I felt like I couldn't breathe, I couldn't talk and I couldn't move. I thought I was dying," she told People. "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."
Now, Lavigne says she's getting her life together again and the ordeal has given her new perspective on life.
"I think, for me, it's a second shot at life," she told "GMA." "I want to go out there and truly do what I love, so I'm so excited for life after this."