Betta with Ichthyosporidium?

My betta fish has lately lost his appetite and wont eat. and the last day or two he has been laying near the bottom of the tank on his side. occasionally, if i bump the desk or tap on the glass lightly, he freaks out and starts swimming around, and he never used to do this before. i looked at him closely and could see that his eyes have become inflamed and his colour has become very dull. He also has fraying of the fins and rotting of the fins. could this be fin rot? i did an online diagnosis, and the result came back as Ichthyosporidium. How would i be bale to treat either Ichthyosporidium or fin rot?