Exactly like the above post but for me it was my front way down low. When i stood up quickly. It scared me too and i asked the dr but he said it was from just the ligaments stretching
Forgot to add: it only lasted a few seconds, then went away.
well, for me, it mostly happened when I got up from bed too quickly, mostly on my side. It felt sudden, sharp, like something stretched and ripped on the inside.