Round Ligament Pain or BH?

I have to agree that a BH contraction just feels like your whole belly is starting to suddenly squeeze. It's not painful, just uncomfortable. I do feel like I've had this sensation just on the lower half (underside) of my belly at times, similar to what you are describing.

With RL pain (which I get A LOT), it happens when I make a sudden jarring movement and have not properly prepared my stomach for the move (like when sitting up to get out of bed). It's a sharp stabbing pain in one particular location of my belly, whether on the side or bottom.