You may want to go ahead and start swabbing the other snakes' mouths out if they were anywhere near this guy. There's a decent chance they've got it (you can pull the bottom jaw aside a bit with your thumb to check for swelling and discharge) but you probably have a chance to nip it in the bud at this point. Also make sure any equipment like tongs or water dishes is sterilized before it's used again or you're just going to see the infection bounce from snake to snake.
The jaw is probably very swollen under it, but the cottage cheese discharge looks like it's coating the whole mouth. The way it's gaping like that, it wouldn't surprise me if it's hardened up. You may need to moisten it with a Qtip before it'll start coming off. Starting at the back corner may work best. You're probably going to have to really upset her to get this cleaned up, but it'll be worth it if she makes it.
For really severe infections where the inside of the jaw has actually scabbed up, sealing the infection inside, I've had to use insulin needles to break through the scabbing; talk about nerve-wracking! But it worked. Hopefully pulling some of that stuff off will open things up and you won't have to do that.
Keep us updated!