Oh Gail...i was going to say PT back would be a good idea, but you say that is not possible. If you can't take more time each week off, how about this odd idea. Would going in earlier or staying later, but taking a long lunch in the middle of the day work? Sometimes I find I just need a longer break in the day to keep me going.
I wish I could give you some of my vacation days as I can't take anymore until next year. Get your docs honest opinion and stay out if you need to. I know you care about your co-workers, but you need to be number one in this discussion.
take care and let us know what you decide.