Kmeb,
From my experience with my sacral stress fracture, I don't think it is unreasonable to ask for another MRI at all. The status of the bones/nerves can change in the period of only one week. I suspect you are at risk of stress fractures too due to your inactivity and your lack of diet. Also a small growth on a bone that might be pressing on a nerve could grow considerably in the period of a year.

Billye