BISMILLAHIRRAHMAANIRRAHIIM.IN THE NAME OF ALLAH THE MOST GRACIOUS THE MOST MERCIFULL.ALLAH THE ONLY ONE GOD.
I agree with dr.Narayan. it think it is enlargement of lymph node of supraclavicular. but you must decide the location on the left or right side. In an adult the following help and it may not help you though
Right supraclavicular lymph node
* Common causes of enlargement: Lung, retroperitoneal or gastrointestinal cancer
Left supraclavicular lymph node
* Common causes of enlargement:
Lymphoma, thoracic or retroperitoneal cancer, bacterial or
fungal infection.
so, it is better to consult to your doctor, now.
ALHAMDULILLAHIRABBIL ALAMIIN.
PRAISE BE UPON ALLAH SWT.