I was suppose to get my period 3 days ago well in kind of came on it's a light pink color. And nothing is really coming out. What causes that to happen.

I was suppose to get my period 3 days ago well in kind of came on its a light pink color. and nothing is really coming out. what causes that to happen.
Are you pregnant? That happened to me when I got pregnant with my first child... around the time I was supposed to come on I just spotted but I never came on... when I say spotted I mean I didn't need a pad but when I used the bathroom and wiped myself it would be lite pink but it was very little.. get it checked out