Some animals don't like to eat when they are shedding. And putting live food in the tank while shedding is taking place can even harm them.
On top of that frogs can go with out eating for some time and it is still considered normal. Are his eyes clear? stomach normal size? And is his poop normal? Is he the normal color he has always been? I heard when these frogs are healthy and happy they are green.
Also can I see some pictures of him?