I have a 22 inch Mbu that has stopped eating and is sitting in the top of the front of the tank with what looks like a lack of ability to get to the bottom. Tank parameters are as they always are and no new tank mates. The only thing I can think of is I was away for a week at Christmas and the heater blew causing the tank temp to go to 69 for the week. She seemed ok after however has gone down hill. Any thoughts?