I think you've mostly gotten the advice I would give from the other responses with respect to taking care of yourself.
I suffer from back problems and chronic pain. I was unemployed for a long time because of it. I've managed to improve, but it took years. So what I'm going to do for her (through you) is to give you a major shortcut to improving her pain and her ability to manage it: She needs to read the book Back In Control by Dr. David Hanscom. Terrible title, but excellent book.
He's a back surgeon who went through his own chronic pain, losing his job and a fellowship because of it and eventually becoming suicidal. His book can talk you back from the brink of that. It did for me. Even if she's not at that point, the book's advice will help her manage her pain - and her reaction to it - much better.
Here's why I know: after reading the book and practicing his simple mental exercises for just a couple of weeks, I already felt remarkably better. This was partly because if even an accomplished surgeon can go through the experience of not having any help from doctors who don't believe you, then this really isn't just some personal failing. Doctors just aren't equipped to properly address chronic pain (with rare exceptions).
I felt well enough after reading this book that I started looking for a job again. I was still having pain, but the way I experienced it had radically changed. I later discovered that a huge source of my pain was from food intolerances, but this just underscored how badly I had been handling it after suffering through it since I was a child. I had improved without first solving the physical reason for my pain.
The problem with pain of any sort (including emotional) is that the signals all travel over the same neural pathways, reinforcing and amplifying each other. Emotional pain can be felt in the body at the site of an old (but fully healed) injury. It feels like physical pain though, making it really hard to solve.
I am NOT saying "this is in her head." I am saying all pain is actually experienced in the mind, and a mind that's in distress can inadvertently make it worse and worse over time. Mine did.
I hope she takes my advice instead of walking the path I did over the course of about 14 years.