Sarah - I had the feeling of a lump after my nissen redo that lasted I would guess roughly 3 months. It could still be that you have swelling in there at this point. I had to be dilated because I was told the lump feeling was that the wrap was a tad to tight. I also had issues swallowing. Do you have that as well ?
Since I was dilated it has decreased the lump feeling some what. Perhaps you should speak with your Doc and discuss your problems, maybe you need the same proceedure which is really common to be done after the Nissen from what I'm to understand. Just my thoughts.
Take Care, Teala