What Causes Vaginal Spotting Between Periods After Taking Qlaira?

Hello. Ive been taking Qlaira for about 6 months now. In the first month I had breakthrough period. I've heard that was normal, so I wasnt worried. Since then, I keep on having spotting between periods. Its starts brown, but then gets bloody. This may last for about 2 weeks or so. The last two periods I have the breakthrough bleeding. Very heavy, but I didnt get an actual period when I was supposed to. I took a pregnancy test the first time it happened and it came back negative. The second time I didnt. I am waiting to see what happens. Is this normal? what should I do?