Boy, you're just getting all kinds of bad advice. The Maroxy isn't really an antibiotic, coppersafe is a really crappy parasite treatment, and bettafix isn't going to help you at all no matter what it is. D:
This does not sound like an external parasite to me. Parasites burrow into the fish's skin and cause cysts to appear. Velvet creates tiny yellowy granules across the fish, you see them mostly gathered in between the fish's scales. Ich cysts are a little bigger--they are white and look like grains of salt have been scattered across the fish. This is likely what the pet store clerk thought you were describing when you mentioned his white bump. If it were ich, it would be much smaller specks all over him, not just one big one. If it were ich, in my experience copper sulfate is an ineffective treatment--from now on I'll never bother with anything other than malachite green when I'm faced with a parasite.
To me, this looks like either bacteria, or fungus. It is most likely to be a gram negative bacteria--true fungus is actually quite rare on aquatic animals and it moves very slowly. It's also extremely fuzzy, much fuzzier than bacteria. From what you're describing, it's not particularly fuzzy--just raised, discolored, and textured oddly. This says bacteria to me, and needs to be treated by lowering the water temperature or keeping it around 76-77 degrees. Many bacteria become highly active around 78-80 degrees and could quickly kill your fish at those temperatures.
I would remove the bettafix. Bettafix is just an antiseptic and a healing agent. It's similar to the effect of putting peroxide on a cut--it's not going to help you if you have a cold because it is not actual medicine. There have also been studies conducted that have concluded that the melaleuca in bettafix and melafix produces fumes that are harmful to the labyrinth organ in bettas and other anabantoid fish.
If I were you, I'd return all those products. Even if they're opened, they gave you bum advice, and you shouldn't have to suffer from the growing dent in your pocket due to their ignorance. You want to purchase a true antibiotic for gram negative bacterial infections--such as API's Triple Sulfa, Seachem's Kanaplex, and Mardel's Maracyn-Two. I always recommend reading this article: http://edis.ifas.ufl.edu/fa084
before purchasing or using antibiotics so that you better understand how they work, how to use them responsibly, and the risks involved.
If you could somehow get a picture, that would be extremely helpful.