I've lost my voice and have a mucosy cough with yellow snot, but haven't had a cold or been sick in a year. I have always had sore knees (athlete) & lung issues when sick. Is this the detox?

Yes, this does sound like detox and the purge started early for you. Your body is developing mucous to wrap up pathogens in, to transport them out of your body so it doesn't have to transport them out through the skin. Sore knees could be from joint issues related to food allergies or your weak area because of sports. You should see some joint relief if it's not related to injury, but the lung microbiome will definitely benefit from this course.