Keep offering her foods, and remove if not eaten. I'd use stress coat, along with making sure you have medications for bacterial and fungal just in case.
Also, you absolutely need 4+ females, to avoid this mess. Too late to say so now, but just for further reference - to save your fish, and the anguish you go through :)
The yellow tint to the scales, is decay. Dead. the scales may fall off and will have to regrow if they can. The infection is probably fungal, please attach a picture. There is also slime coat which looks similar, and is the body's defence to fight off infections. Aquarium salt PRE DISSOLVED can be used 7-14 days, cleaning the water every single day. Some live plants won't survive with the salt. 1-3 teaspoons per gallon gradually adding over a period of time.