Hi, sorry to hear your frog isn't well. To be honest your symptoms and the pictures almost remind me of when my first pacman ever had edema, except for the clear liquid comeing from the bum. But the swelling especially around the back legs really reminds me of the edema, not saying this is what it is but it could be a possibility. Its a good thing you have a vet appointment tomorrow because I think he will need some meds for whatever it is. I seen in another thread that you were asking about the salt baths and yes it could help with swelling and may not. But if you want to give it a try the ratio is 1 teaspoon of Epsom salts for every gallon of water. Just make sure the salts don't have any perfumes or anything added. and I'm going to copy and paste something for you about the salts that I was told by a moderator when mine was sick. Sorry I couldn't have been more help and good luck at the vets.
Cory, was approached by another moderator concerned about high levels of Mg salts could cause problems for frog. I know aquatic frogs are fine with it (i.e. ADFs) during fish treatments in tanks and appeared to help one local sick Pacman (not mine) that eventually did get better. Just letting you know there is a risk involved even if Epsom Salts help with edema. I would stop doing soaks if frog looks increasingly stressed during soak or as soon as edema goes down. If no effect on your Pacman after a couple days; might as well stop it too