Do you have proper humidity and temps now? For best feeding response try to feed him at night, about 30 min after lights are off and temps drop.
He doesnt look good in that pic. Time to force feed him if he doesnt eat on his own. You can start with nightcrawlers coated with reptiboost, cut a piece from pointy end of nightcrawler, coat it with reptiboost and force feed him 1 chunk today, if he is all right, then 2-3 tomorrow. The best would be to force feed critical care formula ( for cats and dogs, available at vet clinics), but it is a bit tricky to feed it when it is your first time feeding.
How to force feed. The best to have a helper who would hold a frog steady, then use plastic card to gently open his mouth and as soon as he do that stick a piece of worm in his mouth. The procedure is stressful but at this point i dont think you have time to waste. You can try to annoy him to open his mouth on his own, gently rub his lips with a worm, sometimes that annoy them to the point they bite and eat it. Try. If not happening force feed. Carry on on pedyalyte baths.


Keep in mind your temps have to be in proper range.