What Causes Lymph Node Swelling On Arm And Neck?

I had an MRI and an MRA today for swelling in neck ,arms, and face, thier's been pain in arms and upper back and into jaws. I have tachycarida and hypotention and take med's for this.
Dr want Eco done at 11:am tomorrow, thier was lymph node swelling on my arm and right side and neck. when I bend over all viens in face and neck close off and swell and I have dificulty breathing. should I be worried or is my DR just being safe? As i have lyme diease and bebseia too