Cytotec(misoprostol) side affect?

Friday I started the medication for my miscarriage, passed the big stuff that night and have been bleeding like a normal/heavy period since then. Well since yesterday I've had bad back pressure and low abdomen pressure, I feel like I just need to fart or poop but I can't. I've pooped once in 4 days. Anyone have this side affect? Thinkin about just takin a laxative to see if that works?