Neutropenia with severe fatigue, what could be the cause ?

ive been having sever fatigue and lethergy for the past one month or so ... Got my blood work done to rule out anaemia ... My haemoglobin was 12.1 and normal ... And no other abnormalities except that my neutrophils were only 36 percent, and the normal range is 50-70 percent ...i have 5 percent eosinophils as well ... Am having relative lymphocytosis due to the overall decrease in granulocytes .... Fatigue, general ill being and slight fever are the only clinical features, what could the problem be ?