Earthworms are fine. I would wager they're close to 90% nutritionally complete enough to be considered a staple diet if fed exclusively. I feed my xenopus a lot of earthworms it makes up at least 70% of my frogs diet and I would say my frogs are very healthy.

I get my earthworm a from bait shops or Walmart bit if you can get some online that works too just store them in a cool place that stays under 70F.

You may need to cut the worms if your frogs are small but they can eat nightcrawlers whole before too long. Stay away from red rigglers or red worms get nightcrawlers which are bigger because red works are toxic or at the very least excrete mucus that frogs find distasteful.

I would keep trying to get your frogs to eat reptomin because its a good food to have just in case you don't have works and I think it helps round the diet out a not too. My frogs eat nothing but nightcrawlers and reptomin.