See your doctor. It could be all sorts of things or nothing at all. You need to be examined and not compare symptoms with strangers.
Recently when I lie on my back, it feels like I have chlorine in my nose. Like when you get water in you nose at the pool. Its not overly strong but its still really uncomfortable. Does anyone know what this could be and how to treat it?
You might want to take a quick look here, but your best bet is your doctor.