If she is in pain, that may be the reason she is not sleeping. But, I have had issues with sleeping my whole life and recently I have found a book to be of help. It's called "The Power of When" by Michael Breus. He states that there are different "chronotypes" meaning the how your biological clock works. I am a "dolphin" as it turns out. If you don't want to buy the book or if your library doesn't have it, there is a lot of information (you can find your chronotype by taking a quiz and recommendations for it) on this website:
https://thepowerofwhen.com
By following his recommendations for my chronotype I am sleeping uninterrupted for the first time in years. I don't sleep 8 hours, but then, as a "dolphin" I'm not wired to do that.