I have been spotting for 5 days now, at first it was a little smear on my underwear and when i wiped, but now it's only when i wipe. what could it be?

Infection? STD?: Most people use "spotting" to mean blood, but maybe vaginal discharge? Either way, you should see a doctor. Any new, abnormal, or unexplained vaginal bleeding or discharge should be professionally examined, even if small in amount. At age 21, an infection is the best bet, and the most common infections are STDs. So don't delay, get checked soon. Good luck!