Questions. . Help?!

I'm 35w3d. I've noticed my stomach isn't as hard as it use to be. The bottom of my belly is almost like a flubbery.. And rest of my stomach is softer then normal i can grab at it; pinch a good amount on it... Hasn't been like this before and I just noticed it couple hours ago... I have tried googeling and seeing what it says but I can't really get much from it.. I have lost my plug; alot of it (rebuilds itself I know) and I was dialated to a 1.5 on Tuesday when I seen my doctor. He said he gives me aprox 2 weeks, and I will not be going my full 40 weeks.. What could be happening to make my stomach lose all of a sudden?

(This is my second child as well--- im 35w3d)