Hello Ryan,
What color is your axolotl - is it white, so that the lump is close to the same color as its skin, or is it dark? When did you first notice the lump? Does the lump seem to be bothering the axolotl? Does the lump look to be filled with fluid? Is there some kind of lump on a human you could compare it with (e.g., a cyst, a pimple, a finger...)?
Axolotls get strange bumps and lumps a lot. Sometimes the lumps just go away, sometimes they become a permanent part of the axolotl's skin texture. More rarely, they are a sign of an infection of some kind.
Without a picture, the remote diagnosis is going to be more complicated, of course. We will need to rely on your description alone. For that reason, it is important that you provide as clear a description as possible. Furthermore, understanding you would be much easier if you could correctly punctuate your texts when giving said description.
-Eva