How was my chest X-ray clear but I’m coughing up snot like crazy

TMI I had a chest X-ray and I have been tested for infection and i have been Covid tested. However, I am still coughing so bad that My so thought I was going to fucking drown in my own snot in my sleep. Apparently I started coughing like hell in my sleep, WHILE I WAS SLEEPING and my so woke me up and rolled me over and I just kept coughing until this huge nasty stuff came out of me and it really freaked him out. He’s convinced that if He didn’t wake me up I could have choked on that.

And I’m not like, on sleeping meds or something. I’m just sleeping a lot because my body is tired and fighting something off. Can they not see the amount of mucus in your lungs in xrays? Because they said it was clear but the shit I’m coughing up is thicker than glue. it looks like yellow and green puss