Tiredness, mild fever, and body pain are most commonly caused by a viral infection such as Viral Fever, but they can also occur with conditions like early Influenza, dehydration, or even nutritional deficiencies. In most cases, these symptoms improve with simple care: take adequate rest, drink plenty of fluids, eat light and nutritious food, and you may use paracetamol for fever and body pain if needed (as advised by a doctor). Avoid self-starting antibiotics, as they are not useful for viral illnesses. Monitor your symptoms, and if the fever lasts more than 3-4 days, becomes high, or you develop additional symptoms like severe weakness, vomiting, rash, or breathing difficulty, it is important to consult a doctor for proper evaluation and tests.