Female Betta weird thing on egg spot/anus

[Heelllooo]

Hello everyone,

Just today my female has developed or excrete some weird thing on her egg spot/anus
It looks like fungus with a white ball inside.
Her egg spot or anus is strongly protuding and it really looks like the thing is coming out of it.
It's only been a few hours since I've seen it and she didn't have anything yesterday.
Could it be fungus ? Could it grow that fast ?
Or is it eggs with fungus on them ? She was looking full since some time.
She is very active, eating and generally acting totally normal. Just yesterday night she rubbed herself strongly one time against a leaf and I've never see her do that.

 

[Heelllooo]

Ok I did more research and it definitely look like fungus. But why there ?!
I planning on either methylene blue dip or treating directly the tank with ESHA 2000.
I would prefer the dip but I don't know if can find methylene blue fast.
Other option ?

And I forgot to mention that I started to inject CO2 in the tank ( yeast jello method ) since a few days.