WG,
Your managers etc are acting very inappropriate and bordering on harrassment. Remember they own thier problems and if they keep on yelling at you and putting you down because you need surgery send off a letter to the home company.
There are plenty of other fast food chains and they are always looking for good employees. Nobody should have to work in a hostile enviornment so keep notes of their behavior including names, dates, times and what was said.
Your manager is not your Doctor and what a stupid thing to say, telling you that you have nothing wrong - surgeons don't operate on "nothing wrong". Go for the transfer.
Good luck sweetie.
Kitt