Today i started cramping and knew my period is due this week. i put a pad on and went on about my day. i went to restroom to urinate and noticed blackish brown light blood. is this normal.

Here are some ...: Some minor variation in color, duration, interval, and amount of period may happen but within a range (personal). How & what could these variations be? Personal experience over time will reveal such. So, what you observed may be okay and deserves a watch and see as long as being comfortable and not getting worse over time. Of course, if persisting or / and worsening, seek gyn-doc's evaluation...