I had a small hematoma (What they call the bleeding/spotting) and had light spotting from week six through week 10. Mostly dark brown but intermittently red. I went to the ER at weeks weeks and I had ultrasounds a bit more frequently (6w, 7w, 9w, 13w, 16w) but I was told they (hematomas) most often resolve on their own if small. I saw my Dr and a specialist and neither seemed too concerned about it and couldn't really see it anymore on the scan. Bleeding stopped at week 10 and I'm 17 weeks tomorrow now, so I'm assuming that's good. By the way, because the bleeding was so light, the doctor wanted to check my urine for an infection, so ask yours to check as that can be the cause too. Hope this helps!
How far along are you? I experienced some spotting with my first. Went on to have a normal pregnancy. Implantation bleeding can occur. But I wouldn't worry too much.