Betta fish suffered shock, now finrot, not doing well

[Jayce0]

About 3 weeks ago my betta suffered a bit of shock, possibly a mix of temperature dropping a bit and generally being spooked (I moved him into another container so that I could re-do his tank, he freaked out when I tried to carefully put him in, he ended up jumping back into the tank so I wasn't able to acclimate him much). For about a week, he spent most of his time in one corner resting. The next week, he swam more and better but occasionally rested at his corner. This week was the same, but I noticed that his fins weren't looking too great (the shock must've weakened his immune system for the time being) and decided to do a water change and went to buy the more expensive water testers and medicine the next day (which is today).

All day today he has spent his time in the one corner resting, but what scares me is the fact that he is tilted upward a bit and he isn't moving his gills much. He didn't eat breakfast. I turned off the light a few hours ago. He is very much alive, occasionally he gulps for air or moves around a bit, I can also see him moving his eyes when I try to get a better look (I'm near-sighted, can't see details too great when I'm not literally 2 inches in front of it).

Is there anything more I can do for him ? I'd hate for him to have the same awful fate of my first betta, who suffered a more severe shock (he got swim bladder and only lasted 3 days).
Oh, might I add that there's nothing wrong with my water quality. No ammonia, nitrates, nitrites, 7 pH... And yes the tank is cycled, it's been running for about 5 months (at least), has multiple plants, little snail helpers..

 

[Kribensis27]

What's the water temp?

 

[Jayce0]

What's the water temp?

77.

 

[Fisch]

I am not sure if I would add meds onto his shock. I believe in lights out, warm water ~80°, little traffic around the tank, some tannins, some good food (frozen bloodworms or daphnia) and daily water changes to keep conditions as pristine as possible. Normally that helps them to come around. 3 weeks is a long time. What changed in his tank? Does he have more current, less hiding places so he is stressed out to the max as he does not necessarily care for his new tank setup?

 

[Jayce0]

I am not sure if I would add meds onto his shock. I believe in lights out, warm water ~80°, little traffic around the tank, some tannins, some good food (frozen bloodworms or daphnia) and daily water changes to keep conditions as pristine as possible. Normally that helps them to come around. 3 weeks is a long time. What changed in his tank? Does he have more current, less hiding places so he is stressed out to the max as he does not necessarily care for his new tank setup?

Ah;; then I suppose I'll try change out some of the water. I ordered some things that'll produce tannins today actually, I'll make sure to put some in once they arrive. I'll try feeding him some brine shrimp when he's a little more active. I mainly moved things around, but I suppose it's true that there's less hiding spots.. I was trying to declutter it since I had put in too many plants, but I'll try to see if I can put any of the bigger ones back in. Maybe I'll put his old ornament back in there. Thank you~

 

[Fisch]

Ah;; then I suppose I'll try change out some of the water. I ordered some things that'll produce tannins today actually, I'll make sure to put some in once they arrive. I'll try feeding him some brine shrimp when he's a little more active. I mainly moved things around, but I suppose it's true that there's less hiding spots.. I was trying to declutter it since I had put in too many plants, but I'll try to see if I can put any of the bigger ones back in. Maybe I'll put his old ornament back in there. Thank you~

I hope it helps and he will recover. Is there a way to get the temp up a bit? What kind of filter does he have and did the current change, or the way the water flows?
He was perfectly happy with the clutter in his house, so he must feel like the husband coming home and find that his wife re-arranged the furniture.