Sounds like really bad gas pains. I get then every now and again
I've also had horrible gas in my stomach that has felt like that. Round ligament pain I get in my sides especially when I sneeze I get a sharp pain iny side and its gone but with gas it makes my whole lower tummy hurt like cramps.
It could be gas as well I've woken up in horrible pain just to realize I had tons of gas on my stomach
Round ligament pain can be pretty bad at times. If it came and went quickly and was a sharp pain it was probably that.
Could round ligament pain? Maybe google it and see if that sounds like it. Pretty common in 2nd trimester.