Sad eyes

Poor Bright Eyes has not had such bright eyes recently. He's been pretty aggro, especially with his brother for the last few days.
It's not because his brother is particularly difficult - he just seems to have a need to get him away and express his dislike loudly and violently.
I've noticed his eyes being quite glassy again too.
I have a bad feeling that it's because he hasn't been on his diet for a while now. At first he didn't seem to react to gluten, but the longer time goes on, the more I think I need to get him back to the GF/CF diet.
I'm dreading it. It's going to be so difficult to take bread and biscuits away again. You can pray for us if you think of it!