Spotting before period

My period is due the 19th but today I noticed that I had some light pink colored discharge which I have never ever had! I have never spotted before and I don't know why I am now? I put a tampon in thinking that maybe I was just starting my period early but I took it out 3  hours later and there was hardly anything on there? Can your period change overtime? Because I've had weird PMS symptoms the past few months that I've never had and my cycle has been irregular and now I have this happening? I don't know what's going on! Any suggestions?