Unusually I Get Horrible-taste Mucus.

Hello. I have what I thought was an ordinary head cold, but when I blow my nose, or mucus runs down the back of my throat, I get a really horrible taste like feces in my mouth. I have never had this before. The only other thing that is different is that I have sort of a headache, but in my left cheek. I am a 50+ y.o. female who has ME/CFS - I usually get a cold or a chest infection when I dont pace myself or am severely stressed. Thanks in advance for any help.