Implantation or period

 My last cycle I had a regular 28 day cycle but I didn't spot I just had my period that lasted for 4 days now I'm in August cycle I ovulate on August 14th and It's been 9 days past my ovulation day now today I'm on cycle day 26 today while I was at work I start having mild cramping  like I was going get my period but my period cramps use to be bad and I bleed very heavy this bleeding is not heavy at all so a couple mins later I start spotting like light  pinkish spotting and mild cramping they come and go I have regular  a 28 day cycle my period is due on August 28th why I'm I spotting on August 25th today