Hey guys! Need some help...

So I had my first period 8/16 after surgery.. lasted about 5 days and I just finished up my fertile window on that was supposed to last 8/27-9/2 with the ovulation date being 8/31... after husband and I had sex last night I was bleeding when I went to the bathroom... not heavy enough to fill a pad or anything and most of it was mixed in with discharge.. it’s the following morning and I see light pink blood but very little. No pain or anything. Happen to anyone else?! Help please... ☹️