Black Molly-Totally messed up

[100570876]

I have a black molly in my aquarium which has been swimming strange and has a weird issue with its fin. I spoke to the LFS where I bought her and he advised that the swim bladder is full of air and to try feeding her pea or holding her a net just above the water and let her thrash-in hopes that she will "fart" the air out. I've tried both more than once and to no avail. Now I have no idea how to try and help the fish as I'm sure its not exactly comfortable.

If anyone can provide comments please do. Thanks!

I have attached a video and pics

 

[Oceangirl]

have a spare tank or tupperware? Or an empty water/milk type jug (clean)? Set up container, add tank water and her. Slowly add 1 teaspoon up to 1 tablespoon Aquarium salt dissolved in tank water over 4 hours. Let her soak overnight, no food. Check the next day. She should be right as rain, my molly got like that after eating an entire 20 dollars worth plants. Try not to feed her for 3 days after that, and then limit food for a while. Feed only every other day.