Other than not going to the toilet as regularly as he usually does he seems ok and isn't really as energetic as he usually is there isn't really any other changes in him.
He isn't on any medication and doesn't have any pre existing medical conditions either. He weighs roughly 2 stone I think we haven't had him weighed lately.
Thank you that was a great answer I will start it straight away. What do I do about him not really drinking water?