Help Swallowtail angelfish swimming sideways

[rickysaucedofb]

Help my swallowtail angelfish started swimming sideways tonight and can’t hold itself upright. I have had the fish about four month and have seen no other symptoms and had no other issues. Attached is two photos and a video.

tank parameters
Salinity 1.025
Temperature 78
Ammonia 0
Nitrite 0
Nitrate 50
Phosphate 0.10

https://youtube.com/shorts/4ZY9QJmg7PY?feature=share

 

[rickysaucedofb]

Update

Found a hole and swelling below the moth with red arrow pointing to area of concern. Any input on how to treat is appreciated.