Suggest Treatment For Itchy And Red Rashes All Over The Body

Hello, My eight year old daughter started with itchy red dinner thighs eight days ago it got worse and then the tops of her feet also started itching like mad for two days the 4th day she developed a rash behind her ears under side of her chin(went away after I gave her texa) and the following days spread down her trunk and legs. She had a little bit of a cough and dry throat however I did not notice any fever. The rash is not blistery but more mottled..the rash next her ears and under chin was really red, almost shade of purple. The pharmacist who I saw suggested texa for skin rashes which really took the rash away when given to her. The rash is not constant but comes and goes, sometimes mottled but sometimes patchy? I thought it was German measles however that is only suppose to pasta few days. My other two children and myself also got one or two random spots but not a rash nature like my eight year old... We ve all had a bit of flu and felt a little tired but are all able to go about a normal day just fine! Please help? I took us all to the doctor and he said he doesn t know what it is?