Metronidazole gel and weird red discharge

I got bv for the first time and was prescribed the metronidazole gel, on the second night I noticed a bit of blood on the very tip of the applicator, the next morning I had lots of clumpy dry reddish brown discharge coming in tiny patches when I wipe, and then a large piece of discharge resembling a piece of vaginal tissue or something of the sort. I made an on-demand visit and the dr said it is not a side effect of the metrogel, I most likely scratched myself while using the applicator and to wait it out? This seems like bs to me because it was literally solid pieces of skin or tissue coming out of me. When I got tested for bv I also tested for all stds and yeast, all came back negative. I am on birth control but have never experienced this before. Is this normal or should I be concerned?