sudden neck fat

Question
Hi Anngela,
I took the guinea pig to the vet.  It is fluid and it has now traveled to the body.  The vet doesn't really know why it has happened.  There is no fever and the heartbeat sounds normal.  We did notice that the guinea pig was drinking a lot of water recently.  In fact, I bought three new water bottles thinking that they must have been leaking, but it must have been him drinking.  Have you seen this before?  The lump under his neck is about the size of a golf ball and it is under his arms now too.  He is beginning to act differently.  He's not as noisy, playful, or happy as he was a few days ago.  He doesn't want to come out of his house much.  
Followup To
Question -
My guinea pig developed a hanging piece of skin under his neck overnight.  Can this be an allergy?
Answer -
Hi Donna.  I seriously doubt its an allergy.  It almost sounds like an abcess.  Is it a lump or just hanging there and how big is it in size (golf ball sized, pea sized, etc.)
I'll be able to offer more advice with a better idea of what you have.
Anngela

Answer
Hello again Donna.  It sounds like diabetes to me, can you have the vet check for that?  I've given cats insulin shots before so I would think you could do the same for a guinea pig.  It really sounds like diabetes.  Sorry I can't offer you more, but it seems like the logical solution to me.
Anngela