What Causes Occipital, Supraclavicular And Pectoral Lymph Nodes Swelling With Breathlessness?

Hello I am a female, 36 years old and have swollen lymph nodes for over a year - they include Occiptial, Supraclavicular and pectoral lymph nodes. I have had trouble breathing for a very long time which I assumed was due to me being overweight. I am getting a little worried now since my symptons are getting worser and of course I don't tell anyone about it. Please help