TMI, but FTM needing an experienced opinion!

I'll be 39 weeks tomorrow. Had an appt on Wed and doc said I was 2cm, softening, and he had dropped half way, so he scheduled my next appt Monday to check progress. Felt great all day at work, but pretty much as soon as I got home (sometime around 3), I felt this urgent need to go #2. Rushed to the bathroom, but nothing would happen. Sat there for a long time waiting for something to change, but nothing. So I tried to get up and continue with my day, but I seriously felt like I was gonna poop myself, so I went back to the toilet. Had incredible urge to push, but still nothing, except a new hemorrhoid. So I finally wobbled myself to bed and took a nap. Hours later, the urge still hasn't passed. Getting occasional, erratic contractions, but nothing consistent. And now I'm getting cramps like I've got the runs, but still nothing will come out, and I'm severely uncomfortable and just miserable. I could cry. Is this maybe an early start to labor, or am I just unbelievably constipated?