I took a pregnancy test the day before my expected period and it was positive but since then I haven't been able to get a positive result. I don't know what is going on I have been feeling nauseated and my lower back hurts a lot. Could I be pregnant or was it a false positive?

Very rarely, and only with certain health conditions does a false positive occur. Are you taking the other tests using first morning urine?

My suggestion would be to get a blood test done at your doctor's office.