Introducing my self + ringworms

Hello,

I'm new here my name is Fatemah, I have 3 cats 2 outdoor males (dabdoob & shaieb) they're both Arabian Mau
and one indoor male (Dumdum) who is a very fluffy white persian mix

A week ago I fostered 2 cats for a week or so, one of them have had ringworms and according to his previous owner "ringworm free now" so I took them to the vets the next day and they only checked them with black light and told me they were ringworm free.

I gave them to a rescue group last week and when I came back yesterday the vet there told me that one if them has ringworms and it's all over him D: the other one was not infected though

But now I think my cat Dumdum has it! I don't know if I'm only noticing it now or that he really started losing hair around his neck?

There's no redness or rings but I noticed very tiny black specks in a small spot next to his armpit, I don't have any experience with ringworms so please if you have any please give me your tips

The vet at the rescue group prescribed me a medicated shampoo that I used on him today but I'm freaking out! He spends most of his time in my room (which is FULL of stuff) how am I supposed to disinfect all of this

@fatemah

Ringworm is a fungus, not a worm, and doesn't cause rings so much as scaly bald spots on the cat.  a Blacklight is only partly effective at diagnosing ringworm, a culture is the best way.  There are a lot of threads on there that you can search for that talk about ringworm.  It is contagious to animals and people, but isn't dangerous in people with normal immune systems, it's just annoying, like athlete's foot.