Shubunkin with a bump or spot on the side?

I have a shubunkin of 3 years old, the fish has been in the same tank (Biorb) and has regular water changes. The fish is the only one in the tank.

Recently the fish has developed a spot or bump on the side. I have used a Biorb first aid kit and added other generic treatments. However the bump has not receded. The fish does not seem to be affected in mannerisms and we have cut down his flake food trying to encourage eating the plants and cucumber pieces - which the fish seems to enjoy!

Has anyone advice on the course of treatment?

The bump is now releasing some white hard paste...not the best description. Its located on the side of his body around the middle. It almost looks like you could squeeze it!...

Had a fish with exactly the same symptoms, but I left it alone and the bump eventually went after a couple of weeks. I don't know if there is any treatment for it, or what exactly it was. Go to a pet store that specialises in fish, you'll probably get an answer there.

Spot or bump...which one? Is it under the skin like a lump? And how big is it? Or is it protruding out of the skin? Is it the color of the skin, or is it red like an ulcer?

try www.bristolaquarists.co.uk. got fish myself. just a point i would like to make. fish like company. a bit cruel just to have one.