Started bleeding bright pink blood yesterday that was only visible on tissue but today it is dark reddish brown blood but my period isn't due for one and a half weeks is this implantation bleeding?

Very good possibility that it could be implantation, I would wait until after your period due date has passed and if you still have not started to take a pregnancy test. Normally implantation takes place 7 to 10 days after ovulation so if you've been tracking your ovulation days you might be able to go back and check further.