Heavy breathing is normally just a sign of stress in a young BP. What is your cage setup (hides, temperatures, substrate, etc.)? The stress could come from insufficient security - hides are too large, not enough hides, too large of a tank without "clutter" to fill it in, etc. Were you moving him/her to a separate tub to feed? If so, there isn't any need and you could actually cause a refusal from the added stress of moving tanks/tubs.