Our cat Stars had kittens about 7 weeks ago. Since then she has looked unhealthy, very skinny, greasy-looking coat. She is about 1.5 years old and before she had kittens she had a shiny coat and healthy weight. At first I figured it was because she'd just had kittens and was too busy with them to care much for herself, but now that the kittens are not nursing much and she doesn't spend much time with them, I'm worried because she hasn't started looking any healthier. She eats and drinks and poops fine, and no other signs that she might be sick. Any ideas?