Something VERY wrong with betta

[RandomWiktor]

Ok, for about a month now, my female betta has had a small patch on her back, kindof where a "shoulder" would be on any other animal, that looked dry (but of course it couldn't be since she's in water). I tried treating for everything: velvet, protazoal infections, ick, external parasites, internal parasites, antibiotics, fungus, etc. to no avail. She has maintained a good weight, eats actively, is very agressive, and behaves perfectly normal.
Or she did, until this evening.
This morning, she was fine, but this evening she seems to be having trouble swimming. Her back keeps bobbing out of the water. When she dives to the bottom, her rear goes up in the air and she has to struggle to stay down. But more worrisome is that when she "exhales," tiny little bubbles (I think?) are coming out of her gills. Is this a swim bladder issue? Or is there something even more serious wrong? She doesn't seem bloated (though its hard to tell since she frequently has many eggs in her), is passing bowl movements fine, and is still trying to eat.
I also noticed a filmy substance that looked almost like oil on the water's surface this morning. The filter is circulating fine, and I haven't added anything to her water recently. None of the other tanks have this substance.
I did a full water change to get rid of the "oil," scrubbed down her rocks and plants, put in a new filter entirely in case hers was leaking something, and heated the water. I've added salts, stress coat, etc. to the water.

Does anyone recognize this condition, and is there anything I can do? The stores here close at 10 but maybe Wallmart has something. I'm desparate to get her better; she's my only little girl and one of my favorite fish. Please help!

 

[littlefishie]

The film is normal, it's protein. You can remove it by laying a paper towel on the water surface and then lifting it up.
Her drifting up to the surface sounds like swim bladder, but don't quote me on that. I'm not too sure about the bubbles coming out of her gills.. I've seen pictures of bettas doing that before, so it can't be too harmful.

I'm not an expert though, I'm only positive on the protein thing.

 

[WILDER]

Sounds like swim bladder depends if you can save her on how far it has progressed, what was the colour of the patch on her also, right try and give her shelled peas if she will eat them you will need antibiotic treatment, add some salt to the tank as well, good luck.
http/www.fishdeals.com/fish_diseases/swim_bladder_disease/