I currently am in the process of getting a diagnosis. I've suffered with chronic pain for only 8+ years. What I have done with a very active 8 year old who does understand and autistic 5 year old who cannot understand is do what I can when/if I can. I've also found that movement, though always painful, helps to make my muscles not so stiff, and allows me to do things.
I grin and bear it most of the time. I have insomnia and am on a trial and error basis with medications(none of them work for me either.) I often find myself having my daughter(8) help out and also my husband who can do everything do the things I can't with my kids. I do push myself to the limit daily because like you I feel guilty, so in the end I do my physical self more harm. I am not recommending you do that. Talk with your specialist and see what suggestions they offer. They are supposed to be trained in how to properly treat all areas of firbo, or so I would believe.
Wish you the best!