Had bad pains day late of period but came on

I was due my period the day before I write this post and nothing so half way through the day (when I normally come on early morning or late at night) I started to get really bad cramps so I go to the loo and I see light pink on the tissue so because I feel like crap I take a sleep. So 2 hours later I wake up from my nap go to the toilet nothing on my pad at all and when I wipe there is nothing but brown sticky looking stuff not a lot but I have never experienced this before also the pain in my pelvic has gone :/ has anyone had this or am I just being stupid although a woman knows her own body and my periods are either light spotting then bam it's there or just bam there u go. I've never had this before could It be old blood? Or just the start of a bad period