What Causes My Abdomen To Fall Out When I Stand Up?

i am 33 years old. i have a 6 yr old daughter through ceaserian. i am continuing with a confusion that whether i am suffering from hernia or diverication of rectii or nothing. when i stand my abdomen seems to fall out with no other seperate small bulge. when i lie down my tummy comes back to normal position somewhat flat as i am not on the obese side. please clarify and suggest excercise if they'll help