In A Horizontal Position (when Lying On My Back) Something

in a horizontal position (when lying on my back) something is sticking out right at the bottom of my stomach towards the right side from the belly button, may be the size of an agg... Nothing is visible when I am standing up, but it's always there when i lay down. I can push it in with my hand and it disappears, but comes back again if I flex my stomach muscles. Not painful and ultrasound did not find anything abnormal. I got this after pregnancy 5 years ago...