I am 17 days late and for the last four days I have been having some brownish blood/discharge. What does this mean?

Could you be pregnant? Are you on birth control pills? Are your cycles normally very regular? It could be hormone changes due to a pregnancy, could be breakthrough bleeding while on the pill, could be your period is due to start and/or is just off this cycle. If there is a chance of pregnancy, try a pregnancy test. If there is no chance... see what happens in the next week. You may just be late, or you may skip this month altogether.