This weird thing keeps happening, maybe a few times a day, often at night. My belly, well, my uterus goes into like a really hard lump! If I feel it it's like rock hard! Then it just goes away. Doesn't hurt or anything. It's usually the whole thing but sometimes it seems a bit more on one side.

I thought it was maybe gas or something, but then nothing ahh... comes out So, what is going on??

Is it just my uterus growing?