I also had severe pain on the left side during my last m/c. Since the
pain was not accompanied by heavy
bleeding (it was about a week after that had stopped) and it did not look like I was having an ectopic (my hcg levels were dropping) they thought it was due to an ovarian cyst that they had seen on the u/s. The pain was so bad it was unbelievable and was only on the left side. It radiated into my back and down my leg. It came and went in waves but was only really bad for about 1 day.