Gray The Hamster

Hi I'm Alex asking for help for my hamster that has a skin disease, he doesn't see a vet because of financial problem. I don't want my other hamster's to get infected because of gray. My hamster name is Gray he is very stubborn, until one day he is lethargic and I start to noticed the redness in his skin. I just want to ask for help so he can take the medicine he needs so that gray's disease can be treated and not be worsen. Hope you guys can help me, thank you so much in advance.