He is a 4yr old British Shorthair. The breed are stocky cats in general but he has always probably been a bit on the big side (just over 6kg). We cut his food down and he did loose some weight (down to 5kg). Now he has lost even more and is actually looking quite scraggy.
He is eating as usual and still seems to have his usual appetite, as he is actively seeking out food. I have noticed also that he is excessively licking and scratching himself. I have checked him over and can't see anything untowards wrong.
He is treated for fleas and worms regularly and cannot see any fleas or anything else on him. I don't know what his poos are like as he goes outside.
What could be wrong with him?