Adam...
that is not good. When they bleach, and then retract that small, it is very hard to get it to recover.
you have to get it to eat.
To feed it, you want super small food, frozen cyclopese, blend sripm up until it is almost soup.
Turn off the flow in the tank, and then use a turkey baster to target feed a could of food around it. Leave the pumps off for 15 minutes at least. Hopefully it will have gotten to asorb some of the food.
Do this 2 to 3 times a day. Change water a lot, every couple days.
Are you using Carbon? With the diversity you will need a lot of carbon. the leathers are great at creating toxic water. BTA can be very sensitive to the toxins.
if you can get it in some direct light, that would help too.