Brown discharge can happen just before or just after a period. Brown blood is old blood, and is just your body's wayof flushing out what was left from the previous period. If in about 3-5 days your period hasn't shown, then it can't hurt to take a pregnancy test to be on the safe side.
See brown discharge can be a sign of the start of your period ,sometimes you may get a different period ,even i have experienced this when i was TTC.
but it can be pregnancy also,many women experience some discharge in early pregnancy.I dont know whether you are trying to conceive or not but i would say wait for a day or two then take pregnancy test with first morning urine.(in case you are TTC or had unprotected sex)