What Causes Soft Knots On Collar Bones?

A few months ago I had what appeared to be knots (soft ones) above my collar bones. Dr. ordered a Ct scan and x-ray of my chest and said the lining of my lungs was thick. He said I have subclinical asthma and gave me an inhailer. the puffines he said was muscle strain. I still feel like I have a little pressure in my throat and feel like I am about to have an anxiety attack sometimes. I also have a thyroid disorder and take levothyroxine for that . Ultrasound of thyroid shows nothing. What do you think is going on?