I have 2 pet fancy mice, I think one is sick or being bulled?

If she is sneezing, she could have a respiratory disease. I don't have mice, but I have rats who have this problem. My one rat was sickly like you described. I gave him some antibiotics and luckily he has been healthy ever since. If Shirley is being a bully and not letting Laverne eat, they maybe will have to stay apart.