One of my gold barbs developed a large lump on its head about a month
ago, and it has continued to slowly grow.

Now it can't swim and just struggles on the bottom.

The strange this is that its hunger, color and activity before the
sudden drop to the bottom of the tank were normal. Other fish that had
gotten sick with columnaris acted markedly worse until we gave it
treatment.

Here are pictures:
http://hubpages.com/hub/My_Sick_Gold_Barb

Does the fish have any hope?

Thank you for helping me.