First off, a bowl is a horrible situation for a betta. They need an actual tank with filtration. Secondly, putting two male betta in a tank together will guarantee the death of at least one of them. They fight. A female is also risky – the most successful situation would be a sorority tank of only female betta.
PLEASE research proper betta care and upgrade your fish’s living conditions.
GOod morning
It’s hard to tell from a photo, but it could be something as simple as a clogged hair follicle or a pimple, which hopefully that is all it is? I would still call the vet and make sure, but try not to stress yourself out over it. Good luck!
I agree with Sarah. Also a bug bite, wound, etc? Dont get too worried. See your vet when you can about it. Also if she isn’t spayed I would inquire about that. That’s a bigger worry for me.