https://www.medicalnewstoday.com/articles/318791
Hyperalgesia is the principal symptom of opioid withdrawl but it can have other causes. Imagine being in a permanent state of opioid withdrawl.
Twelve years ago, coincident with developing undiagnosed diabetes, I developed neuropathic hyperalgesia that fluctuates randomly but is negatively correlated to blood pressure, i.e., the higher my blood pressure, the less the pain. Remarkably, feeling good is a sign of bad health. My hyperalgesia interacts with other chronic pain conditions, mostly pain in my muscles when they contract. The stronger the muscle contraction, the greater the pain. There is no muscle injury causing this pain therefore exercising does not aggravate any injury. Exercising just hurts.
Hyperalgesia also amplifies other physical discomforts besides pain, e.g., itching, urge to urinate, defecate, cough, etc.. It is even possible to feel too hot and too cold, all over, at the same time.