URGENT! Whites tree frog very sick!

[bratstone]

I bought my whites tree frog at pets unlimited. While there, I noticed one other frog besides the one I bought in the enclosure! He had dark bruise like spots on his back, but my frog looked healthy so I bought that one. I Got
him home, and he never really did seem very active, but the last few days I noticed him being lethargic, and I also noticed that his belly was bloodshot making me think red leg. Well he's even sicker now, and he's developed green spots on his legs and he can't jump at all! When he attempts to
his hind legs knot up and overcross like a pretzel! I gave him a melafix bath and he's in his own hospital container away from my two other whites tree frogs! Does anyone know what this is? Or encountered it before? What should I do? I reeally don't want him to suffer