Tiny jumping mites infesting cage! Panicking owner!

[Michaela]

I've had my Pacman for a few months now. But I've noticed a increase in the amount of these mystery bugs. They are tiny, tiny brown bugs/mites that jump. They don't look like fleas...can frogs even get fleas?
They're infesting the cage though and I have no idea where they came from. The wood log? The moss? The soil? I'm so worried about my little Lyagushka!
What should I do?

[Lija]

Pic of the tank and the bug? How often do you clean the cage, change the substrate? What decor do you use?