One of my cats who is approx 17 has started doing this weird loud cry which sounds like a child. It goes on for about 15 seconds then tails off to a quiet cry. She'll run about and then sits at the top of the stairs shouting. She's very active for her age and eats well. Apart from looking a bit thin and I think she may have lost hearing a bit, she seems okay. It's been going on for a while but is getting more frequent. Any thoughts?