This is going to be a very brief post, but I knew that I wouldn't be able to express these thoughts within the character limitations of a Tweet, so chose to include it as a blog post instead.
There isn't much specific advice out there about there about writing whilst struggling with chronic illness. However, what I have found is that the information that is out there in abundance - along the lines of "finding time to write whilst juggling a career and six kids" - can be easily adapted, to apply to our circumstances. We are busy, and have very limited time for writing, and the fact that what we are spending our time and energy on is being ill, rather than doing positive and proactive things with our lives, doesn't mean that much of the "busy lifestyle" advice cannot be applied to our own situations. Not all of it can, of course - but take what you can, from what is out there.
Keep writing, and keep believing.