Worried

Heyy, I want to update about my Kim today, he won't eat much as he usually do. Im soo worry about him and lately I found something on his skin, its a brown/yellow thing but it is inside part of the skin(meaning, i have to make him strech all part of his body to see) Im so scared, is that a fungus? If it is, I need to find anti-fungal but where can I find it? Pet shop in axis(where i adopted Kim) I think they have. But, no money lah(another problem). Hope he will be fine. I gave him dried shrimp but he dont seem like want to eat that because he eat a little tiny bit and I also gvae him pellets and he dont eat it AT ALL! OMG, hope he will be find... :(

P/S : I don't know what to do anymore.