Help...

My Last period was 8th September lasted approx 5-6days. According to the app I ovulate today 21st September. I don't know my cycle length as I was on the pill for so long so I've did the average length which is 28 days. My Ovulation tests are negative from 19th. Went to the toilet and wiped. This the start of my period coming? This bleeding implantation or some sort of discharge?