Is Sampson showing any signs you would relate to HyperT flaring back up?
Have you tried increasing his daily food intake? I know that can be hard sometimes with more than 1 pet.
How was he with the cooked chicken added on his food?
Avoid biting when a simple growl will do
The Spirit Lives As Long As Someone Who Lives Remembers You - Navaho Saying
Vindication ~ For all those pets who became sick or lost their lives from tainted pet food