Have had light cramps for 2 weeks, today had bright red blood dried in underwear, none when I wiped. One week until period. Implantation? Spotting?

See your provider. Irregular menstrual bleeding is extremely common and there are MANY different possibilities. At the very least, you should see your gynecologist or primary care provider. Fortunately, it sounds like you don't have very much bleeding at this time, so it is certainly not an emergency. But you should not let this go unchecked. Check it out and nip it in the bud before it becomes a real problem.