Spotting meaning??

At a loss,I am on the pill which causes me to skip my periods which is great and has been the case for the past four/five months with no problems. however I woke up this morning to spotting, not enough to be a period but 100% blood. I have been feeling off the past week however nothing out of the normal for me. I have not missed a pill and therefore very unlikely to be pregnant. Is there any other reasons for spotting? I've never had this and making me anxious :/