HELP MY BETTA IS SINKING

[Lily]

Hi,

my Betta Fish started acting weird a few days ago (around last Sunday May 21st and Monday May 22nd). I first noticed she was staying still in the bottom of the tank after a water change but I don’t know if it started then or after. She is still staying in the bottom for long periods, sinking or resting in a leaf or under one of the floating decorations for what I think is support. She’s also swimming weird. 
 

Here is a video with some footage of her sinking and staying still:  https://we.tl/t-2Q6Jb0OOGR 

Everything looks good in the tank (is a 5 gallon Fluval Spec tank), I added a picture of the water parameters test results (that are normal) and the temperature in her tank is around 75-76 F.

I went with some of her tank water to my local aquarium shop and they say it might be swim bladder disease. So I stop feeding her for two days and yesterday night I feed her a little bit of pea (as advices by the worker in the shop) but she’s still acting weird (the video is from today). I don’t know if I should start giving her food again. 
 

please help me, she’s normally so active and now she is just standing still. I’m so worried and don’t know what to do. 

[Shadow]

I am no expert, but parameter wise...is your pH reading 6.0? That is awfully acidic. Should be closer to neutral for Bettas stateside, I know imported ones prob are use to slightly acidic, but thinking that is more 6.6-6.8 at worst. Could have something to do with it. My betta has long time he chills on the bottom or under plants, but regularly comes to the top for air. Likes to become more active when my mother comes into her office. 

[Stef]

In addition to the low pH, have you checked the flow?  The Fluval flex tank has a strong output even if the internal pump is set to low (min). I cover mine with a piece of pre filter sponge. Bettas also like warmer water. She’d be comfy at 78-80F. 
 

Can you test for Ammonia?

Edited June 1, 2023 by Stef
Adding ammonia question

[Cinnebuns]

That PH test is bottomed out. Its actually possible the PH is below 6.0 and we can't know by how much. That could be a major issue. What is your source water PH?

Edited June 6, 2023 by Cinnebuns