I'm sorry to hear that Sarah. I don't really have an answer for you, except would it be possible to split his feed up into more feedings? If he can't or won't eat much at a time, can you split it into smaller feedings, several times a day? Also, it might be that he has an abcess or something that is making him sore and not feel like eating. I'd get the vet to come check out his mouth, even if his teeth were done recently, something else could have happened in there.
I can sympathize with you -- as soon as I got to the barn this morning, I noticed Annapolis has dropped weight since last weekend. The barn owner came over and told me that Annapolis seems to be having trouble eating his soaked alfalfa pellets (although it looked like this morning he had managed to eat them all, as well as his Safe Choice)
Of course, I immediately thought about his teeth and remembered that Doctor Beckham said last time she floated him that he had a wave going on with his molars and although he has most of them still, there's not much left of them. She just did a manual float at that time, so Brody and I talked about it and he mentioned that Waller Equine have a traveling equine dentist (not just a vet who does floats).
So after the holiday weekend, I'm going to call them and make an appointment for them to come and check Annapolis and see what needs to be done.
I wish I had more of an answer for you about Fantacy, hope you get it figured out.