Huge Bump forming on my back

25 year old male. Height 6.0, weight 180

Yesterday I noticed a bump on my back the size of a golf ball form right at the base of my neck and top my back. It is not tender or sore but feels rubbery and i can move it around.

I did not notice it this weekend but just noticed it yesterday, and this thing is huge!! Is it a cyst a swollen lymph node, or something else?