There is a chance there has been some permanent damage to her nervous system. Unfortunately there is nothing that can be done for that. When you integrate her back into the main population be sure to watch for the others picking on her because she isn't quite as strong as the rest. This doesn't always happen but there is always a chance. She is now "disabled" and while it may not be enough to keep her from the other fish, it will require a bit more supervision on your part.
In regards to the medications and replacing the kanamycin with another, that's a difficult thing to suggest at this stage. First of all, I see no need for an antibiotic to be used with your fish at this time, which is what kanamycin is... a broad spectrum antibiotic. The reason that one particular medication is something I suggest in some situations is because it is absorbed through the skin, whereas others are not. This ability at rapid absorption can be beneficial when there is a severe infection that needs to be treated quickly to save the fish.
There is a lot to choose from in antibiotics, however, not all fish can tolerate all medications. That means I only prescribe meds on a specific as needed basis. Different infections call for different types of treatments, also. Some antibiotics are a bit more harsh than others, some are more mild than others, and thus fish respond differently according to the problem, their species, etc. There is also the added problem that some antibiotics treat for gram negative bacterial infections, some treat for gram positive, and then of course, the broad spectrum that treat for both. Medicating fish properly can be challenging, especially via internet because there is no ability for me to do the needed lab work to identify a specific bacteria strain, etc.
Its great that you have ordered books to help you, I will always encourage that, however, to rely on a few books is a dangerous thing. There is a lot that goes into learning about fish medicine and books can only teach a small range of that. My experience goes way beyond books (both college text and independent authors) to include hands on, necropsy/autopsy study, experimentation, and lab work and research. There are a great many illnesses in the fish world that over the years have become immune to medications that used to treat them successfully. One of these is a common bacteria/fungus combination found in bettas.
A lot of people are not aware that water chemistry also plays a part in medicating any fish. Water chemistry, things such as pH, ammonia, nitrite, nitrate, etc. can greatly affect not only the effectiveness and effects of a medication but also how the fish react to it. Without experience with the many types of medications out there, it gets to be a guessing game. This is why I always encourage people to ask for help from someone with experience in fish medicine before dosing any fish/tank with anything. It is very easy to use a wrong medication which can have adverse effects on the fish and at the same time allow the actual problem to get so out of control that the proper meds no longer have the desired effect. More fish die from mismedicating than from the actual illnesses themselves. This is where having experience in diagnosis plays a huge role in success/failure.
Your situation is a good one to use for an example. When you first asked for help you were convinced there was a parasite/worm problem with your fish. Had you treated for such, you would not only have seen your fish get sicker, but by the time you figured out that your suspicions were wrong, your fish may have been too far gone to save her.
It can be difficult to find a qualified person to help with these things, which is why I try to make myself available as much as possible for anyone who asks for help. Since I do this for a living offline, with my husband as a consultant when needed (along with a number of vets and other specialists), I stay "in the loop" when it comes to the medical field. My training and experience are always an on going process, along with my research. I can't force people to ask for help.. but I will continue to always encourage it.
So, knowing all of this, the best thing I can tell you now is that if you have a problem in the future, feel free to ask me for help. I will do all I can every time, and if medication is needed I will prescribe it as I see the need for it. The reason Finland and other countries regulate certain medications so strictly is due to the dangers in allowing people to use them too freely... so as long as you have a dr who is willing to help you I think you are in a good position. Keeping some of these meds, especially antibiotics on hand for free use at a later date is just a bad idea. Not only because of not knowing for sure what and when to use them, but also because they have a shelf life and once expired, are less effective (sometimes completely ineffective) which is a waste of money and medicine that could have gone to help someone else.