dying of cancer?

Question
Hi,

My name is Ali and I have a 5 year old male american satin guinea pig. My question is that is he dying of cancer. I seem him eatting all the time but he is ALL SKIN AND BONES. I would be surprised if he weighted 1 pound thats how skinny he is. And I also see him drinking A LOT. A bottle a day. I had him since he was 1 month old and he's always been such a sweetheart and loveable.
His eyes are sunk in and his back legs are very weak. He trips over newspaper ( I line the cage with and then add pine woodchips). I feel very sad and bad. :( Do you reccomend that I have him put down? Is he suffering? I went to my vet that takes care of my dog and he said to just feed him more hay and see what happens. That advice didnt work very much. I would love a second opinion and advice. Thank you so much for your time.
Ali & Piglet

Answer
Hi Ali.  I'm not sure what more I can tell you.  It sounds like he is very ill.  He needs to see an exotics vet, not the normal cat/dog veterinarian.  Mention everything you've just told me - drinking excessive water, still eating but no weight gain, stability problems, etc.  For whatever reason he cannot use the nutrients he is putting in his body and if something doesn't get fixed fast he's not going to make it.
Anngela