Greyish phlegm. Symptoms. kindly help

Hello doctor Since last one month I am having greyish phlegm on and off. Sometimes blocked nose also due to AC. I don't smoke nor have any other symptoms. No fever no pain nothing. Just greyish phlegm mixed with clear phlegm (something like greyish spots ) and sometimes it's dark also.  No bleeding nothing. Feels like phlegm stuck in the throat and urge to cough and take it out. I am very scared as I never had it before but yes sometimes which went off by itself. Is it any infection or something else. If I google it scares me. I am already an anxiety patient and have done therapies for the same. It scares me to the core if I hear anything. Please tell me doctor do I need to worry. I have done chest x ray PA view also which came normal. Rest i don't have any other symptoms. Kindly help 🙏🏻 thank you.