Branchial Cleft Cyst, neck, head and shoulder pain

Around 16 weeks ago a lump popped up on the left of my neck under my ear after dinner. I waited a week to see if it would go down, bit it didn't so I made a doctors appointment. He wasn't too sure what it was, so he sent me for an ultrasound. The ultrasound showed an egg shaped clear filled thing. The results weren't too clear, so they sent me for a MRI, that came back inconclusive as well, so I was sent for a biopsy. The biopsy returned negative for cancer (YEA!) but even though they aren't sure what it is, they have settled on a branchial cleft cyst. I am 34, have never had any major illness, nor had a 'pinhole' seeping or otherwise. In the past week it has grown larger and I have pain, not in the lump itself, but in my neck, down the front of my shoulder and on through to the tip of my middle finger, down the back of my shoulder blade, more to the middle of my back, and up behind my ear to about 2 inches above it. The pain isn't constant, but the ache is. Sometimes, throughout the arm, it is more of a swelling numbness that aches terribly, that I find sitting on my arm or putting it behind me and leaning against it is the only way to stop it. Has anyone one else had this pain in relation to a lump, not a slipped or herniated disc? Thanks.