What Causes Brown Discharge Instead Of Periods?

hello. I am on the second month of loestrin 24 and instead of my period it was all a brown discharge and very little red blood. I have been bloated, nauseous & constipated for a week or two now. I have not had sex for about 3 months but I took a pregnancy test anyway and it was negative. I have had 2 other light periods since sex also. Is there anything wrong with me?