I honestly think you may have been let go because you're on a witch hunt. Every single facility on the planet is doing at least something wrong, and I'm not saying you shouldn't advocate for what's right, but it's how you do it that matters. I have actually reported a coworker before for negligence and it went well for me. It's important to remain calm and state only the facts-how you feel about the situation emotionally isn't relevant. Be professional, be polite, don't place blame-just state facts. It always helps to get other professionals' opinions on the matter before you go reporting as well.
As far as CNAs passing meds, are you sure they weren't QMAs (I think that's the acronym)? I have no idea if your facility's practices are legal or ethical; at your next job, ask to shadow for a few hours so you know what you're getting yourself into.