Bump on redbreast sunfish

Helloe everyone.  I haven't been around much due to life, but I have had my red breast sunfish, Morsel, for a while, thanks to the members of this organization and forum. 

This week he developed a bump on his head.  It appears to have grown over the last few days.  If anyone has any idea what it could be and what I should do about it I would appreciate it.

I do water changes of 50% or greater about weekly.  I introduced some fathead minnows for him to him to enjoy 5/16.  Not sure if they could have given him something, but they never have before.  I haven't pulled out the test kit yet for the water because of the regularity of changes.

I wasn't able to attach pics but I have linked to them below.

http://www.thecrimso...0523_141209.jpg

http://www.thecrimso...0523_141205.jpg

http://www.thecrimso...0523_141202.jpg

Morsel did not survive the night.

I'd guess an internal bacterial infection; may have been slowly destroying organs for a while before the bump appeared.