A very long period...?

So, I normally have really heavy periods, but they are usually quite short (3 or 4 days). Last Monday I had a PT test and was curious if there was any way to at least lessen the flow, so I asked my doctor, and she told me to skip the inactive portion of my birth control pills, and just start a new pack. I started my period prior to the PT test, did as my doctor told me, but I haven't stopped bleeding; it's been 10 days. I mention the birth control because that's the only thing I've done differently. What could the problem be? I'm out of town at the moment, so I can't go back to the doctor just now, I was just curious if anyone has had this problem, and what the problem might be. I'm not in any sort of pain, and all of the other menstrual symptoms are gone already.

I know this question might sound funny, but I'd really appreciate some serious answers. Thank you.