Light spotting, any advice?

I'm about 6 weeks and 2 days. I had HCG testing done last week and it all doubled as it should and then had an ultrasound, but was only 5 weeks 5 days at the time so we couldn't see a heartbeat yet. I have been having cramping on my left side since before we even found out I was pregnant and the doctors cant seem to figure out why, happens mostly when I'm stressed. Today I had some light pink spotting that I only noticed when I wiped and only happened twice and now i havent noticed anything but I also have lower back pain like I would normally get when I'm getting ready to get my period, which has come and gone up to this point. Is the spotting anything I should be worried about? I have an appointment with the nurse practitioner Wednesday, just not sure if I should call before then. This crazy worried momma is losing her mind!