Widespread pain affecting many joints or muscles in the body associated with lack of energy, lack of sleep, generalized fatigue, irritability could be due to disease called fibromyalgia. Some other symptoms include muscle cramping, presence of muscle tender points and sometimes depression. In this disease, a person may have been subjected to various lab and radiological tests but without any definitive diagnosis.
The theory behind the pain is some hormonal changes and disturbance in the immune system. Once the diagnosis is made, this ailment can be treated with physical therapy, few lifestyle modifications, and medications. Some of the activities like yoga, swimming, stretching exercises can help reduce pain significantly. It also helps in improving physical flexibility and reducing muscle stiffness.