Okay here are some tips. Frogs have this sense for water. Any nearby watersource and they will go to it. I would say turn on some water around your bathroom and leave it out. Tree frogs love hiding in shaded areas so try looking under things like house plants or under smooth surfaces. Just hope he is still inside your house. A good time to look is during the day when they are hiding from the heat. They won't move much so you can narrow your search. Around dawn is when they start moving around for water/food. If he ever gets outside say bye bye. Hope this helps.