I took the abortion pill 3 weeks ago. i had unprotected sex after, we know better now, but i just got a faint pos. could it be from the old pregnancy?

Maybe: One can recheck a urine pregnancy test in 10-14 days, and if still positive, see the Ob-Gyn doctor. The question then would be whether the bHCG is from the last pregnancy or a new pregnancy. For now, if not trying to get pregnant, a couple must use good birth control. Abortion is not good birth control, because you have to destroy your baby fetus. Prevention is the way to go.