I have had a couple of sliders for 3 years now with no problems, but recently one of them has started to react strangly after being fed. He eats the same sort of volume as always, but after eating he is trying to bite himself in the neck (this does look strange) and is using unusual actions with his front legs in an action that looks like he is trying to clear something from his throat.
I am at a loss to understand what is going on here and need some help if possible.
He also is basking under an artificial UV light almost all of the time and does not really show much in the way of activity. When he is fed he seems to be active enough, but something is not right.