How exactly is your cage setup? Size of cage? Temps? How are you measuring your temps? Humidty levels, what are they? Does the frog have access to at least one hide? What's its weight currently? Do you actually see the ribcage or spine protruding/showing? What other foods have you offered, if any?
These frogs, as far as I know, will accept wide variety if they are healthy and if the husbantry is correct, such as earthworms/crawlers (pending on the size of the animal), fish, crickets, mealworms, quail, small mice and pinkies.
There's a lot of questions unanswered, so if you could expand and answer as many as you're able, it'll allow the rest of to hopefully help but right now, the information provided is too vague.
Two other suggestions, one, if the animal has not eaten in 6 months, have you tried calling a qualified Vet that deals with herps? And two, I suggest getting a gram (food) scale. You can pick one up at any farming or supply store for a fairly cheap price. You could also run a search on amazon.com and type 'food scale.' But with a scale, you can moditor and keep track of its weight loss. If it's dramatic, seek a Vet's assistance, that's your best bet, as the frog many need antibiotics for internal paracites (if any).
Best of luck!