Betta Fish: Rip Nico

So this is a bit of a vent/rant but I need it off my chest. I have just come home from a 12 hour shift to find my Koi Betta Nico whos been with me from almost the beginning of my journey in owning fish passed away due to dropsy. And to say I am utterly crushed is an understatement. Ive had so many memories with him from sleeping lopsided on the sponge filters making scared something was wrong when I first got him to him being a picky eater and always swimming to the left of the tank to see me everytime I entered the room or when he would follow my pencils when Id sit at the desk next to the tank and sketch. I recently got him a betta bed so he wasnt laying around randomly and he took an immediate liking to it. He spent so much time in this bed than he ever did without it being there that I thought it must be a new norm that hes claimed the betta bed as his territory in my community tank and I soon saw less and less of him within the tank itself yet he was still eating and still lively so I didnt think much of it. I came home to see he began pineconing out of the blue and immediately rushed him to my spare empty tank and started him on the only treatment I could get my hands on. I checked websites of pet shops in my town and went to 2 pet shops within walking distance and no where sold epsom salt, KanaPlex or Furan-2 so I knew it was going to be a fight for him. I began treatment as he just laid breathing in his bed that Id moved into the tank with him and he was fine this morning and even managed to eat 2 of his 3 pellets but once I came home he was gone and I am so angry at myself for not seeing the signs sooner but also for nowhere in a close radius to me to sell the things I need to make sure my animals are okay. My room feels empty without him. I am absolutely devestated.