Do you mean those flukers orange cubes? You can give him Pedialyte for now, but it doesn't compare to the other stuff in the link I gave you, which has a ton of minerals and nutrients in it. Pedialyte just has a few electrolytes in it as far as I know.
Also, I wanted to add that unlike reptiles, toads don't typically bask in the sun to absorb D3, so they would probably rely on their food for d3.