Swollen lymph nodes for a year/growing.

I'm 23 years old, 130 lbs and 5'6 in height. I've had swollen lymph nodes for almost a year now. I've had two ultrasounds of the neck done for it. The first one they were swollen but my doctor thought nothing of it. Then I went for the second because they hadn't gone down and it showed they actually became larger and are now above what is considered normal size.. yet my doctor still believes I'm fine. The other doctor that looked at my ultrasound said I should get an MRI or CT scan of the neck.. but my main doctor insists I'm fine. I also have been suffering with consistent, severe chest pain on the right side and I struggle to breathe 24/7 and it's starting to really bother me. I can't even walk upstairs or down a hallway without gasping for air. Because of my chest pain I also had a CT scan of my chest done and it shows I have atelectasis in both lungs and a small ground glass nodule in the left major fissure. My doctor also said I'm fine with this too but I'm still concerned.