She has the bump for 2 weeks now. Initially she is still very active and eats well. And now, she still eats well but sits at the bottom of the tank most of the time. We tried Epsom salt for 1 day then switched to aquarium salt after talking to the aquarium staff. We started the Internal Parasite Guard yesterday and it doesn't seem to help. Any one can help please! Thanks.

There was a similar issue on this about a week ago.
You should probably switch to another medication for bacterial infections
Along with the use of melafix. Sounds bacterial...

Can we just stop the Internal Parasite Guard and start the antibiotic? Should we do partial water changes and if so, by how much? Thanks.

You didn't mention the size of your tank, but
If you do a 10% water change then replace the activated carbon and let it filter all the old medication out of the water (like overnight), it will be safe to continue with the new treatment the next day.

I had this issue in October with my common goldfish; he was getting a swollen lump, equal on both sides of his body just behind his gills. He started being real lazy, hanging out at the bottom unless he was being stimulated or fed. I tried everything I knew before realizing that this is a case of infection. I used maracyn two for 5 days and the swelling disappeared; he is perfectly fine now.

Can everyone please check the dates on threads before responding, this one was started in 2007.
I have seen so many old threads dug up lately and it pushes newer questions down the list.