Fluttering?

I've had a baby so I know what a big kick feels like problem is I didn't get a postive result for a long time, and had very low hcg. Now recently I've been peeing more, and feel fluttering like stomach spasm near my belly button and lower. I recently tested but got a negative. And I don't wanna rush to the dr for the blood work just yet. Does anyone else get this feeling or am I crazy? Lol sorry but it's been freaking me out these last couple of days