painful bms

Kelsey
For the past week or so my bowel movements have been like torture. Horrible abdominal cramping (to the point of dry heaving), nausea and I break out in a cold sweat. My stool is not hard. If anything it's soft. I have horrible hemmroids also (which are left throbbing afterwards for days). I'm on iron supplements and I've taken fish oils to help keep the stool soft while on iron. I only go every second day or so and they are massive. But I feel like I'm dying every time. (Or scared it could put me into labour early). 
28 weeks with di/di twins. (I don't remember this at all with my singleton). Any suggestions?