new (scary) symptom in 3 week cold battle

For more than three week now I have had a cold. It started with sinus pressure, stuffy nose and a sore throat, typical cold symptom. about 5-7 days after the symptoms started I developed a cough that is lingering even after the other symptoms are long gone. it's a cough where i have to stop what I'm doing til the episode is over. sometimes i cough so hard that i get a sharp pain in my head. The cough is producing mucus, which vary day to day, one day it yellow and thick, the next it's thin and frothy. the next it so hard to get out i almost have to vomit to clear my throat. but today i felt my neck and there is this pain, my throat isn't sore just this one spot , it right in the middle where my collar bone is. this is completely new, even when i swallow saliva or food, when it get to that spot it hurt, like the food or spit is rubbing against something. it doesn't feel like something stuck in my throat. can someone shed some light on this, please, this new symptom is freaking me out.