Blood after sex!!!!

My husband and I had sex on Feb 22,23,27 and today the 29th my, period ended on the 21nd of Feb (we used the pull out method) after sex today I went to use the restroom and notice like a table spoon of blood on my panties, I wiped and still a bit more blood but less than a table spoon 3hrs later I recheck and there is no more blood just a light brown discharge in color. I don't itch nor does it smell at all. I don't supposed to get my period till the 17th of March according to my app calendar and I'm also ovulating today or so it says. What can this be? I know it's not old blood from my last menstrual bc of the way it looks. Help!