severe lower abdominal cramping

Christy
I am currently 6 weeks 5 days pregnant. This is my fourth pregnancy this year. All others have ended in miscarriage. Every other time (with the exception of an early loss at 5 weeks), I didn't know I was miscarrying. Only possible sign was a lack in symptoms...maybe.
Today I am almost doubled over in pain. Do you think I'm miscarrying again? Any possible was this is normal? I've had no bleeding but the pain is strong. Other symptoms (nausea, breast pain, food aversions) are all still there. 
At what point do I go to prompt care or ER? Or do I just wait and see? I've never experienced a sensation quite like this. Not totally unbearable but difficult to stand upright and laying down doesn't feel any better.