pink/brown discharge

my period normally starts sometime between the 25th and 27th of every month and lasts about 5 days and is fairly heavy. this past period was extremely light. started the night of the 27th just spotting, then light bleeding for 3 days then spotting the last day. now for the past few days I've been having pink/brown mucus like discharge which never happens. could it be because we have sex on my period (never done that before but this period was very very light lol). it's starting to drive me nuts.