Ladies

Hey Ladies I have a quick question and would love your help so when I came home from work I went to the toilet and on my underwear there was brown discharge maybe you would say maybe spotting I have no cramps nothing just this was there when I came home as u can see I had sex on the 1st 4th my period started that night 13th and 19th July... I know this is a long shot but could it be implantation maybe as I have never spotted when I was due to ovulate I know only way is to test but don't know what to think I have my covid jab on Monday so will need to do a test before then just to make sure ... what would be my odds ??... Will keep an eye on it and see does it turn into a flow or not I guess also