It sounds like you are either going to have to find another job or go after Wal-Mart with a good attorney. I would try going through the proper channels first, but with my asthma as severe as it is, there is no way I could work there.
Did you have asthma before you started working at Wal-Mart?
CeeBee, I can't believe you have had the same problems I've had at Wal-Mart. I know they will do anything to save money. So there's no telling what the problem is.
Macrip, keep us posted and let us know if we can help you in any way. I don't see how you can work there.