What Causes Low Grade Fever, Lack Of Appetite And Tiredness?

Low grade fever about 2 weeks. No appetite. Tired no energy. Sleep ok. No nausea , no diarrhea. No coughing. No stomach cramps or grumbling sounds in intestinal track. Get short of breath after light amount of exertion. Get chilled takes about 2 hrs under blankets to get warm again. Drink plenty of water at least 1.5 liter a day. Urine is a bright yellow. No matter how much water I drink. No pain before or after urinate. Just feel exhausted after a days work. I lay down for awhile I kinda feel ok but just not myself. . I am a truck driver and all over the country but don t stay long in one place. Age 63 female no medications.