How Can Severe Abdominal Cramps During Pregnancy Be Treated?

First day of my last period was Aug 11/17. Had an IUI. Saw doctor for early ultrasound last week at 7 weeks 4 days pregnant. He saw two separate gestational sacs. One had strong cardiac activity and the other had weak cardiac activity. He said he expected the weaker one to stop developing and rebsorb. Last night (8 weeks 1 day) I had some mild to moderate spotting of dark red blood and severe cramping. Is it possible to miscarry one twin rather than reabsorb it? Could I still be pregnant? Can’t get another ultrasound until Wednesday because of Thanksgiving weekend in Canada. Didn’t figure there was much point of going to the ER on the holiday weekend as they don’t have an ultrasound tech working and I’d likely just be told to wait it out. I’m just concerned about the amount of cramping (was on the left side mainly and was painful enough to keep me awake all night).