Is there any chance you could be pregnant??
If you had a miscarriage recently, some tissue could have been retained from the amniotic sac. That can make you have a trickle of bleeding, it happened to me. You might see if your doctor could do an hCG test (to see if there is anything retained that would give you a low hCG count) and an ultrasound. You don't want to keep retained tissue, it can give you scar tissue in the uterus and make it difficult to carry a baby to term.