Hi Gracie's Mum.
If you're having cramping and red blood then it's okay for you to present to the emergency room. Unfortunately at 5w 3d I don't know how much an ultrasound would be able to see. I had an ultrasound at 5w and all they could see was a round sac, no foetal pole. Really nothing.
Have you had your HCG tested? I'm sorry that you're going through this. It could be so stressful. It might just be a waiting game to see what is going to happen.