Discomfort in tummy

Okay so since baby has been born I've been feeling this pain in my belly. It's not comparable to indigestion, gas, cramps or nausea.. it's similar to the feeling of having a heaviness or gut feeling like something is wrong. Kind of like a "rock in the pit of your stomach" type situation. What is this from? It gets worse at night for some reason but it doesn't happen every day.