I have some concerns. I am sexually active, I do take contraceptives.. But it wasn't time for my period and I bled 3 days then stopped... Then on my period I had brown discharge.. Couple weeks later I have the same thing and some slight bleeding. Do you know what this might be? This happened all in one month.

It may be many things, an infection, other medical issue, and of course a sign of pregnancy.
Birth control is not 100 percent, even women using birth control and condoms at times get pregnant. You will need to wait till the time for your period, and if no normal period or no period at all, do a test 10 days latter with first urine of the morning