Hi. My 11 Month Old Has Been Running A Fever

Hi. My 11 month old has been running a fever going on day 5 today (it has gotten all the way up to 104.7 with the average being about 102). She has no appetite (though she is drinking her bottles still for the most part) and is very lethargic (definitely not her spunky self). She is negative for any ear infection and her twin sister is not sick...Any suggestions?