My cat Scotch is roughly 9 months old - although we aren't sure because I got him as a stray. He still eats kitten food, however he is a healthy 9 pounds already. He is not overweight, just a big orange tom cat... However he almost always has runny stools, which smell unbelievably bad. I have tried Purina kitten chow, and a less expensive brand, but neither makes a difference. I also feed him wet food every few days, but it doesn't change due to that either. Should he be eating regular cat food? He also has problems with hairballs, but most brands of food made for that are against use in kittens. Any tips??