I'll be 26 weeks tomorrow, and I'm classified as high risk due to a short cervix. 

And I am extremely constipated, and I have been for the past week. 

Not too long ago I had a feeling that I had to poop (finally) so I went, and nothing, I stayed there and just waited and tried to push it out. But then I got a cramp all over my lower stomach, it was painful, and tight and it lasted for about 20 seconds. It wasn't unbearably pain or anything, but it definitely hurt worse than a normal cramp. I don't know if that is a contraction, Braxton hick, or just because of my constipation. 

Anyway after that, I stayed there for a little while, still feeling like I need to poop, I could feel the poop coming, but nothing, eventually I just gave up waiting, and wiped anyway, and the tissue looked like I just had diarrhea, but there was nothing in the toilet, and I had a long yellowish green thick discharge coming out of my vagina. 

I just want to know if this is something I should be worried about, I'm in a lot of pain right now, but I don't know if it's constipation or early labor