Sorry to hear Clive seems to be declining Beryl, they do all age differently & some more quickly than others so I don’t think knowing exact age helps much anyway.
They are so sensitive it could be that he’s pining a bit or just disturbed by the loss of his room mate.
A little bit of a change up of clean might help a bit.
I can’t remember now did you ever try the evening primrose oil for his fur loss? It does have other benefits too so might be of some help now.