My 6 year old spayed female seems to be drinking more water lately and even though she always had an odd body shape (head always seemed small compared to 'body'), her body area (as in stomach/abdomen) looks very large. She also sleeps by water bowls and lays down as she drinks. Eats well. Hard to monitor her litter box habits....I have 7 cats and 6 litter boxes. Doesn't seem in pain when I feel her tummy area. Any ideas?