Hi. Thanks for your query. Noted the history about your Mother having viral fever as explained by your Doctor and she is having fever, vomiting and was hospitalized for the same, developed reddish rash with itching. This is called Viral exenthema and can occur due to many other reasons too, allergy to medicines, foods , adulterants and so on. I would advise you to send me the pictures of the rash as it helps sometimes for on-the-spot diagnosis. Give her antihistamine for control of the rash and itching. Oral steroids may be needed in some cases. Apply Lactocalamine for its soothing actions. Consult a Dermatologist to get a better diagnosis and management.