30 weeks pregnant and having odd feelings

Hey y'all, I'm 30 weeks and 6 days pregnant with baby #2 and I've been getting these odd feelings at the top of my abdomen. They don't feel like contractions, it feels like tightening but when I touch around my belly even when the tightening happens my belly is soft. I don't think it's the baby moving either cuz it has happened while she was moving and I was able to feel both at the same time. Any ideas? Would it have anything to do with having an anterior placenta?