I Have A Lump On My Arm Can It Be A Tumor A Cyst Or A Knot?

I have a marble size lump under my skin near my elbow. It is kind of mushy what could it be?

Below my elbow there is lump
now sore the size of a small egg.

I have 1 too found it a week ago its wierd feels hard, but doesnt hurt when I touch it

I had a tumor in my arm it started off as a bump down by my rist and the doctor told me it was carpel-turnel .  But it soon moved up to the middle of my arm and looked like a ball on top. Soon after I was in pain also . I went to a speci list and he showed me the xray it looked like a spilled class of milk in the bottom of my arm. He told me we needed to get it out right a way "don't wait" they went over major arterially and now I have a very long scar but thank God-it was not cancer.