This one is tricky because if you had a positive pregnancy test last week then yes, you were pregnant when you took that test. Spotting can be an indication of a problem with the pregnancy, like a miscarriage, but you're saying that it's just spotting without a flow. Typically with a miscarriage, there's a flow, cramping, and clots. I don't know if you're still pregnant, but you definitely were last week. Here's what you should do:
First, take another pregnancy test. As long as you don't have a flow of blood, you should be able to take another test. If it's negative, then I would take that as a sign that you're experiencing a miscarriage.
If the test is still positive, especially if the test line is still as dark as it was (or hopefully, even darker), then there's a good chance you're still pregnant, and the spotting is some kind of breakthrough bleeding which isn't unheard of in the first trimester.
Once you've taken the test, whatever the result, call your doctor or find an OB and let them know what you told me - that you had a positive pregnancy test last week and now you've been spotting for several days. They'll possibly want to do two blood draw - one when you come in and another a couple of days later to confirm if you're pregnant and if the pregnancy is progressing or ending. They may also do an ultrasound. I know that this stuff can be frustrating, exciting and scary all at once so hang in there and just get down to the bottom of things.