Is a posistion considered equivalent if they transfer me to 9 stores in 6 months?

I am an MGT(manager trainee) at a large company and have been since 1997 and was typically transfered once every couple of years, I had to have my spine fused and went on leave for the surgery. Upon returning to work I have been moved 9 times. I am being used to cover for STL's(store team lead, which is below my posistion) and occasionaly other MGT's who are out sick or on leave. My surgery was on 1/27/11 and I returned to work part time in april,then full time the begining of july. The closest of the stores was 4 miles away but the store they have currently sent me to is 36.6 miles away I have no choice but to go(nor does any MGT)however, they say they don't send anyone more than 20 miles from their home, and while they said I could bill for 10 miles each way per day I still have no choice. The reason they give for moving me so much is that they crrently have no "permanent" store to put me in. When I went on leave I informed them of my return date of 3 months, as long as they would make accomadations for my not being able to bend, twist, or lift for a short time (or 6 months if they were unable to). I returned right at 3 months. What are my rights? Can they legaly do this? Do I have any options other than just waiting for them to put me in a "permanent" store?