Sho caught it years ago when he would give me the slip and run outside to roll in the dirt.
He had it all over his back and sides, in little patches. I wasn't given a medicated shampoo, but I did wash him every couple days with his regular shampoo to help keep itching down.
Since he was younger then and it was on his sides, he got the 'old sock sweater' as I call it.
It kept him from rubbing the affected areas on DH or I, or any of the furniture, helped keep him from scratching or licking at the spots too. Always wash your hands and change out of any clothing you were wearing after handling.
He only had one medication, ketoconazole pills. That and his immune system itself got rid of the ring worm in a couple weeks (after treatment started).
Is it possible just to keep your cat in one room, even a bathroom? A cage seems rather small for that long.
Edit: The fuss is that you don't want to end up having to wash and treat all your cats for it.