My cat is constipated and it's giving her hard time in the litter box. Her stomach is hard but not at an exaggerating point. She had this issue before when she was a little kitten so i used to give her olive oil with her milk when that happened. But now she's a cat and people say it's bad to give her milk, not mentioning that she herself won't drink it any more. She only eat's cat food and sometimes white chicken. Nothing else. So how do i help with the constipation problem?