Menstrual-type bleeding when not on your period?

I am taking the prescription birth control Loestrin for bad menstrual cramps but it also functions as my primary birth control method. It is my first month on Loestrin; I switched from Ortho Tri-Cyclen Lo, which I had been taking for two consecutive years. I am experiencing menstrual-type bleeding today but my period should not be for another week at least. I have heard of women who have had early miscarriages and mistaken them for their period. Is it possible that my birth control has failed and this is what I'm experiencing? I figure it's better to be bleeding than not but any unexpected occurrences make me nervous.