I have a father who, after smoking for 25 years, quit last March. Unfortunately, over the past couple of years, his stomach has grown significantly. However, when he presses against his stomach, it's just the stomach wall - little to no fat outside the abdomen muscles. Also, his navel has protruded out some.

It looks almost like he's pregnant. Could this be a massive tumor inside his stomach/intestines, or is it something else (something I hope is less serious)?

He doesn't want to go to the doctor, probably out of fear of what it might be. While I realize that doesn't make it any better, I was just hoping for some possibilities while I continue to prod him to go.