First of all, congratulations on your pregnancy.
With both of my children I experienced cramping for a few weeks, (at times quite painful). My doctor was emphatic that if I noticed any spotting, to go to her office and be checked. To ease my mind, I had early ultrasounds. I'd suggest getting one yourself; it's reassuring (and exciting) to see a normally developing baby. This way you'll know for sure that everything's alright.
Call your doctor/nurse and explain the situation; she/he may want to see you anyway. I'm sure your doctor will be understanding of your concern. Ultimately, listen to your body and request that your doctor do what you want.
Good luck and again congrats!
S.