Writing a book is so fun! I keep stumbling upon many websites that have much to offer. Today, I found a website of a young woman who has Lupus. She developed what is called "The Spoon Theory" which is a way of explaining what having a serious chronic illness feels like to the person who has it. Please check out the link and read her article. It is not only brilliant, but aptly describes how it feels to live with invisible chronic illnesses.
http://www.butyoudontlooksick.com/articles/written-by-christine/the-spoon-theory-written-by-christine-miserandino/