Strange sensation in stomach, feeling of something going up the ribs that has to be pushed down causing intense pain. Hernia?

I have some weird thing going on in my stomach. After having my last baby I could tell something was different because I could palm my uterus and feel it until it went down. But most recently (my baby is now 18 months) I can feel different organs in my stomach, like the size and pulse of my big artery . And sometimes something goes up under my ribs and I have to push it back down (thats the only thing that s been painful, it feels like the same thing when a baby s foot does that, but I AM NOT PREGNANT ). A friend that s a nurse thinks it s maybe a hernia? Any ideas?