Menstrual cramps?

Hi there. I just hit 31 weeks today and all of a sudden since this morning I'm having what feels like these little (very light) period cramps... I'm not too alarmed because they're not regular and I can still feel the baby kicking and squirming all the way in my ribs so I'm sure it's not 'real' contractions (also they're barely painful). But they feel totally different from the feeling I thought were Braxton Hicks, because those just felt like my belly getting really hard and kind of like stabs in my side from running on a full stomach (only not in my side but in my belly). So it's an entirely different sensation.