Implantation bleeding or something else?

So, my period is supposed to be next week for me, but for 6 days I’ve been having a brownish pink discharge where if I don’t wear a tampon it’ll stain my underwear. I’ve been worried as this never has happened to me and the pregnancy test I took days negative. I’m worried if it’s something worse, but my fertility doctor and gyno kind of blew it off stating it’s nothing to worry about. I’m 33, I have PCOS and I’m worried about this being a sign of menopause which terrifies me as I just start a journey in fertility. Anyone have any ideas?