Is it normal? i have light brown kind of mucus disharge

i had my 2nd daughter 3 months ago and got my 1 st period nov 28th. ended on the 3rd of dec. for the past two days i have a light brown discharge sometimes with a little mucus...doesnt smell. i am not sure what to do? the last time i had sex (3 days ago) it was sore at first. what could this be???