What could be causing a bitter taste at the back of my throat?

I don't suffer from acid reflux, I don't have any problems with my teeth, I'm not sick or congested, but lately I've been having a bitter taste in my mouth, especially like an aftertaste after eating. It's sort of like the feeling you get when you use a nasal spray and it drips down your throat. My tongue also feels a little tingly, like its got some sort of a film on it, but nothing is noticeable. I'm not taking any medications either. Anyone had something similar?