My mum's guinea pig keeps squeaking constantly. He lives with 2 other piggies and gets on fine with them. Mum will give him treats, cuddles everything but he keeps squeaking. I've checked him over and can't see anything wrong with him but I'm not a piggie expert so I might be missing something. I've heard it for myself- it doesn't seem related to anything it's just constant. Is he just vocal or is there something we're missing?