Sometimes, and totally randomly, cycles can decide to be a week early or a week late, and that's not usually a cause for concern. In your case, since I don't know your other dates or whether or not you've recently had unprotected sex, I can't give you a good idea on when or not you should take a pregnancy test.
If you suspect that your last period was actually implantation bleeding than anytime now would be a safe time to get an accurate pregnancy test.
You might also look up a pregnancy test timing calculator, like the one on the CountDownToPregnancy site to get a better idea of when you should expect your next period and when you can take a test.
This way, you can figure out if your symptoms are a sign of early pregnancy or a sign that your period is on its way.