Hello, Welcome to Healthcare Magic. I have read your question fully and understand your concerns. You have said that the rash does not look like eczema, could it be like a psoriatic rash or a resistant fungal infection? I am sorry; I cannot diagnose the rash without having any further information of how it looks. As your sister is having the rash for past 3 months, and as you have tried various different creams but to no effect, you need to see a dermatologist and request for a biopsy. The dermatologist will take a small skin sample and send it to the pathologist, who will study the specimen under the microscope and give the diagnosis. This process will help to identify the skin problem of your sister. The dermatologist may also take some blood tests to rule out chronic skin problems or other conditions which can be associated with skin problems. I wish your sister a speedy recovery. I hope this answer has helped you. Thank you Regards Dr Sunita Sayammagaru