unfair demotion ,pay cut?

i have a very good attendance record at work. recently i did not work on a saturday that was scheduled overtime (it was only a three hour day) i havent missed a full day in probably two years. i was sick and didnt get up in time to call in. i was transferred to another department where the pay is less. i was also suspended for one day with pay. can my pay be cut to what everyone else in that department makes? no one else has ever been transferred when they have been suspended and our policy is to be suspended for 1 day, then 3 days, then 5 days then you are terminated. this is my first suspension do i have a legal case if my pay is cut? there is another employee who missed 3 days of work because she was sick and she didnt call in on the last day she missed yet she wasnt even reprimanded and this happened three days prior to the day i missed can i do anything about this obvious favortism? i work in tennesse.