She hasn't changed the bird's water since Wednesday?!?! WHAT?!?!

Is the water in a bowl or in a water bottle? If its in a water bottle, it can stay ok for several days because the bird cannot get anything in it, and mold/bacteria takes longer to grow in closed bottles, however, if its in a water bowl, it needs to be changed once a day at minimum. I change my birds' water sometimes even 3 times a day, because they like to throw food in it, which can cause bacteria growth, and can make the animal sick. Bacteria grows FAST in water, and not changing his water can be harmful for his health. You NEED to have your mother change his water on daily bases. Seriously.

Food and water should be changed daily.