Weird pregnancy symptoms

Every so often, after I hit 15 weeks, my stomach feels super heavy and like a big round rock is just on the inside of my skin about to fall out with the slightest movement. It doesn't feel firm like there's a rock but the skin feels like something heavy is pushing on it from the inside. Is this normal this early in pregnancy? I imagined feel this way maybe around 25 weeks or more but I'm not even halfway through week 17 right now. I for sure am gonna need to buy some sort of belly support (band or tape) soon.