I Have Smelly, Thick, Yellow, Circular Mucus Plugs About Every

I have smelly, thick, yellow, circular mucus plugs about every week or so. that have a thin layer of mucus on the inside while there is thick mucus on the outside of the circle. I have to try to hock it up but sometimes it won't come out and the mucus seems to be getting thicker in my throat and nose. No other medical problems and I've had this going on for over a year and a half or so.