I Have A 6 Years Chihuahua Named Tabby. Weighs 9.5lbs. Her Stomach Is Protruding. Constantly Hungry, Especially At Night. Looks For Food. Restless. What Do You Suggest?

I worry about her. She had 2 cysts removed from her bladder earlier this year and she is on a special diet to help prevent this from happening again. I am concerned about her. She is beginning to wheeze some. What do you suggest? Thank You, Kristen A Chester