All you can do is continue changing water using a double dose of Prime (amount for the whole tank) until the cycle re-establishes and the ammonia and nitrite drop back to 0.

Happy New Year 2010!

Stress can trigger Ich, but it's still the same parasite, so it should respond to treatment. I would do a large water change and then restart treatment.

Cories can be sensitive to medication so using three at once may be too much for them. For a clear case of ich, only Exit is needed. I would discontinue the other two meds, and if you haven't already, add extra aeration until the course of medication is complete.

That may be a female filling up with eggs, ready to spawn.

The skin peeling sounds like some sort of infection, so I would treat it with Esha 2000.

It's not overstocked, but the advice is poor, as Neons and Otocinclus need the water to be cooler than a Betta prefers. Neons can also be fin-nippers, so they may nip at the Betta's fins, and Bettas are potentially quite aggressive and may bully the other fish. Usually, we'd advise that a Betta be kept alone in a 40-litre tank.

Click on the forum name you want to post in (e.g., Tropical - Help and Advice). At the top of the page is a green button marked "New Topic." Click that and make your post.

Looking at their web page, yes, if you want the tank to look less red/blue.
https://ciano.pt/en/produto/sistema-led-cle120plants/

No they can't be used together. Give the Flubendazole 48 hours to work then do a 50% water change and add carbon to your filter for 24 hours to remove the rest of it before treating with Esha 2000. Don't forget to remove the carbon before staring the Esha 2000.