I feel for you – you do have several challenges to deal with. I don't have any easy answers, but there are a couple of things you might want to check out. If you haven't already done so, you might look into computer work you could do from home. That way you could work your own schedule and take breaks whenever necessary to help keep the pain level down.
You might also look into getting some occupational therapy. An occupational therapist could help you either learn things you could do to make your current job less painful or train you to do another type of work that wouldn't increase your pain levels.
Good luck to you!