My period is now 4 days late ,today i started discharging brown spots.this has never happened before. i always use protection. what could this mean?

Hard to say.: First, whenever there is a change in the pattern of a period in a sexually active woman with reproductive potential, pregnancy should be ruled in or out. If your pregnancy test is negative, repeat in a week. If not, it's not uncommon to have a change in pattern of period occasionally. If it happens again, get checked.

Could be: Could be anovulatory cycle, irregular ovulation or pregnant. If you are sexually active do a home pregnancy test because protection fails sometimes. If negative, the brown spot is probably your period getting ready tot start. See your doctor if no period in another 4 weeks. best!