This is new - period seems different

My periods have always been the same no matter what, the bleeding was heavy and bright red with painful cramps that caused me to stay home in bed having to use many pads. Last month my period was the same way, this month something new happened, my period was a day or two late which i didnt think much of or anything but when my “period” came it started off light brown then to dark brown and then to a dark red brown and didn’t fill up a pad at all. After that my hubby and i had intercourse which after i bled light red for a few hours and it went away. Now with all the walking I have to do I spot brown but not enough to fill a panty liner. What’s going on? Has anyone else had this?