There is no treatment we can provide for you. If this is indeed fluid buildup you will need a drug called Furosemide and will have to inject he frog with it in the front half of the body just beneath the skin. This will open the tubes in his kidneys and begin to flush out fluid. With how bad off he is there are no guarantees. I'm sorry there is nothing more we can do.
I hope you can get help for him. I wish there was more we could do.