This is my first pregnancy and had the same thing. I was freaking out but my Dr told me as long as I'm not in pain or the blood isn't bright red like from a fresh wound then it's probably just old blood from either a previous period or excess from the implantation so not to worry take it easy. That is what the Dr told me. :)
Although its hard... Try not to stress!! Enjoy each day being pregnant. And its normal to spot a little during the first trimester.
Try to rest as much as possible
Stop worrying.. it is normal in the first trimester