hi, fever of long duration has multiple causes like tuberculosis , connective tissue diseases ,malignancy , as u r having raises ESR there is likelyhood of all these diseases ,so check for tuberculosis anywhere in body ,and malignanct also ,but if u hv joint pain and rashes with hair fall ,multiple oral ulcers with constipation ,eye problem ,dryness or redness of eyes then u should be testing for connective tissue disorder