Period again?

I had my second girl September 18 and I got an official period October 23 to the 31st. On my 6 week checkup, doc said everything was perfect but now I'm on my period again. I started it yesterday out of no where. Is this normal and is it my period? I haven't had any sex with hubby yet so I don't know why I'm bleeding again. I dont remember having 2 periods in less than a month with my first. It's not heavy, it's very light almost like spotting and I feel some what of a very mild cramp here and there. Has anybody ever had this before? Thanks ladies.