Another Betta at bottom problem

My betta is kept in 10 gal, planted tank. Temp is 79-80. Food is Hikari Gold, 4/5 per day. Once a week or so he gets a treat, i.e., dried bloodworm, etc.
About 2 weeks ago he became very lethargic, mainly just sitting or lying on the bottom, only coming up for air or food. His coloration became dark and pale, and grey, with lighter grey under his eyes, and near his gills. I fasted him for two days, and gave him tiny piece of a pea, but that did not help. After reading many posts, I moved him this morning to a hospital tank with heater. In the pictures, his tail and bottom third of his body are on the bottom of the tank. Sometimes he is completely on the bottom.
I should have posted and taken pictures before medicating, but I proceeded to put Jungle Fungus Clear and 1 teaspoon per gal of epson salt in the water when he first went in the hospital. The hospital tank is 5 gal. In the tank I will be able to see if he is pooping, and what it looks like. It is very sad to see him like this. I have had him for about a year. I also read that peas are controversial, and it is probably better to feed him frozen Daphnia, if I can find it. Anything else?
Thanks