Hi, I have two whites tree frogs that are roughly a year old but yesterday I noticed that one of them was just laying on the floor which is very unusual for my frogs as that are normally high up on their glass tank. When I picked the frog up he seemed limp and cold so I gave him a warm bath in water which perked him up for a little while but as soon as you put him back in the tank he just sat there. He has also gone a darker shade of brown than his usual green. The temp in the cage is 25 degrees and humidity is at 80 %. They have access to fresh water dusted crickets and UV 2.0 light. I hand fed him a mealworm earlier today and I don't know if i should continue doing that as he doesn't seem to have the energy to catch any crickets. He's currently sleeping on the floor in a shady spot.
-Just a note I have only just added the UV 2.0 bulb they used to just have a red heat light.
-My other frog is fighting fit (in the same tank)

Any ideas of what might be wrong or advice would be great ?
Also if i do need to keep hand feeding how many mealworms does a 1 year old frog need he's about 2inches long ?