Cramping is not always a sign of miscarriage-the uterus growing causes some cramps, too. Spotting also may or may not be a sign. I miscarried twice, and still had some spotting with my son--placenta previa is the most common cause and sometimes it is no problem and sometimes it does cause miscarriage.
My doctors always told me to try to relax and I know how hard that can be, but honestly there is very little you can do to avoid a miscarriage (outside of taking good care of yourself and being sensible anyway).
You need to get checked out just for peace of mind, and so they can check for other stuff like anemia, etc. I hope you're already taking your vitamins--they are good for you. And, morning sickness is usually a good sign!
Good Luck!