Should I be concerned?

So I’ve been on the combination pill for almost 3 months now, and I’ve has intermittent spotting, but 12 days ago the spotting started getting heavier and hasn’t stopped. It’s all brown, old blood and has been at a relatively low flow (the most I’ve had to change a pad was 3-4 times a day). I’ve also had cramps everyday and occasionally it burns a little down there. It started up when I began taking an iron supplement, and at first I thought it was associated with that change (sometimes new supplements can affect birth control a little). But now idk, it’s getting increasingly more painful, heavy, and the burning is worse. I’m not sexually active and I don’t currently have a yeast infection that I’m aware of (I could always treat it retroactively of course). But yeah, what do you think might be going on?