It's okay if he doesn't soak often. Toads like to be a little dry. So long as the water is provided in case.

You may want to switch to crickets and/or earthworms or nightcrawlers. They are easier to digest and don't cause impaction. Just a thought .

If I had to guess, I'd say the spots look like a fungal infection, though I am not a vet. I would recommend moving him to a temporary tank with paper towel as the floor, changed daily. Still provide his water dish. Change the water daily. What type of water do you use?

Most amphibian infections can be treated with metronidazole which is a liquid antibiotic/antifungal/antiprotozoan medication. It is prescribed by a vet. I would also ask for silversulfadiadene cream to apply to the spots daily.

If you don't have a local vet you can try emailing a photo and then calling Dr. Frye. He is a vet in Michigan who will often send you the medications with guidance. He helped me to save my 5 retf's who were very ill. They had both fungal and bacterial infections. Long story made short...you can read my post if you'd like. Anyway, he is wonderful.

If you can't fond a local vet to prescribe what you need and take a look at him or if it's too expensive I can send you his email and phone number.

In the meantime, remove and clean the rocks with a mild bleach solution and be sure to rinse all residue off. You can also boil the rocks for 1/2 hour. Be sure to rinse in dechlorinated water after the cleaning before you place them back into his tank. Wash down his tank too. Rinse thoroughly.

You may want to switch to coco fiber substrate? I'm sure he'd love to burrow when he is healed .

Keep us posted. I will help as much as I can. Good luck!