Embarrassing Q: What do I do about recurring bad breath?

So…kind of embarrassing problem here, but lately I’ve been noticing that I’ll frequently have bad breath. I know it’s not from eating something because it’ll show up even if I don’t eat something. But, essentially, I’ll wake up with pretty bad breath in the morning and then if I brush my teeth not long after, it may return not long after that. And even if I eat something and then brush my teeth and go to class (my usual pattern in the morning), by midday or so I’ll notice that I have bad breath again (usually I just notice a bitter taste in my mouth).

So lately I’ve just been packing mints and it seems to work, but I’d rather know if there’s a more long-term solution and if anyone has any experience or advice.

(Sorry this was supposed to be in general).