I feel that this is probably not the right answer to your problem, but I had the yellow hands & feet while still in the hospital. My problem was dead skin from calluses. I worked construction and used my hands continuously in rough work along with being on my feet continuously. After being in the hospital for a few months all the calluses began to turn yellow and looked terrible. My wife would soak both hands and feet in warm water and literally scraped off this dead skin a little at a time. It took a long time to do this as, like a lot of GBS patients, my feet and hands were very sensitive to the touch.
As mentioned before, this is probably not your problem, but the mention of yellow hands brought back this memory. Hope you do find an answer.