Hard immovable lump upper arm

Hi - wondering if anyone has had anything like this.. I found a small (pea-sized) lump on the upper part of my arm, not quite inside more facing outwards towards my right breast. It doesn't feel like it moves and almost feels like it's attached to a cord. It is quite deep and the dr has suggested it is not a cyst, but rather a lymph node. I am absolutely petrified and my referral isn't for another 2 weeks. 
Has anyone had the same? And any help or suggestions with controlling anxiety? I have gotten so bad I can barely function. Thank you x