Hi , I've Noticed For The Last Several Months Above

Hi , I've noticed for the last several months above my left clavicle where my supraclavicular lymph nodes are, that it is swollen and standing straight up in the mirror it pulsates . It isn't like this on my other side . I'm 20 years old and last year I got diagnosed with some gastrointestinal issues I was prescribed medicine for. I feel a dull ache in that area and the last 2 months have been going through physical therapy because of muscle imbalance on my left side . They had given me a neck and cervical spine mri and determined nothing was wrong I just had been favoring one side over the other . I'm very concerned as to what this is, I have an appt with my general physican on friday because I feel as though I can't let this go any longer .