Fish has knot that developed

I have a fish in my mother in laws tank that has developed a knot on his side behind his eye. Something I have never seen..the tank is a 55gal 8 other tank mates..water tested fine last time I tested have not got a chance to test today (4 children keep me otherwise occupied) I have included some pics...if anyone knows what this is please help me. He looks like he is bloated and has lost some color as well...

This is him before...


This is him now....


The tank...

 

Could be a tumor or infected wound.
Best treatment would be increased water changes and see if that makes a difference.

 

Told by LPS that this is hole in the head disease??? Anyone confirm?

 

Generally, hole in the head is an erosion or depression type wound not a bump.
It's usual causes are poor tank conditions and poor diet ( usually excessive feeding of gold fish).

 

Well it's not a big bump anymore....it's now smaller and looks like it split on the back side....pic to come

 

 

I this point, I believe it is a healing bacterial infection.
Broad spectrum antibiotics and increased water changes are the best course.

 

Broad spectrum antibiotics? Any specific brand you recommend?

I currently have him in a 10 gal isolated tank....and I have a box of API general cure

 

Ok so since I put him in the 10 gal his wound started healing so I did not use the antibiotic...however he is extremely neurotic right now. Keeps trying to jump out of the water and has rubbed a sore onto his lip running into the glass...**** do I need to do??? We have out stress coat in the water to try to calm him