Hi, okay, here is what you need to do ASAP.
-take a pic of what sounds like prolapse to confirm. While waiting for reply look around for vets who treat amphibians as a back up.
- place a frog in clean, wet papertowels, chanded daily, put a plant of sorts, I like these handing silk ones, you can get them bigger, stick to the side and half of it will be on a ground. Frog love hides like that. cover 3 sides of the enclosure, sprinkle sugar on the prolapse.
- DO NOT feed! DO NOT try! Not until the prolapse is under control. Keep in mind even if/when it retracts the chances of repeat prolapse is very high and you should stuck to nightcrawlers for a while now. But only after the situation is under control. IF the prolapse doesn't retract on its own you need vet and surgically fix that, otherwise it will end very badly....

based on on what you wrote there was nothing that would point on any fault of yours, husbandry is spot on, temps could be higher, substrate seems a bit dry, but it all really minor things, by any means could not result in prolapse. The most common cause is feeding high chitin containing food ( mealworms, super worms), parasite infestation and ingestion of something that can't be digested - keeping in husk, moss would be the most common.

Keep us updated, I'll try to swing by tomorrow.