spotting and cramps 6 weeks pregnant

Took 5 pregnancy tests Monday showing positive. Yesterday night I started to experience spotting and off and on today also. The blood isn't dark. I also have some cramps on my left side (but I have been experiencing cramps almost everyday. Usually at night). My first appointment isn't scheduled until Thursday. Today is Saturday. I'm worried about miscarriage. I'm guessing that I'm about 6 weeks pregnant.