Severe pain in shin bone worse when shins get cold. morphine gives 70% pain relief. ?

What illness underly: What underlying disease do you have that requires morphine to treat? Bone pain could be metastatic cancer pain. Talk to the doctor who prescribes your morphine.

Shin pain: Consider stress fracture, referred nerve pain. Consider x-ray or other imaging to check for infection, fracture, tumor. Morphine seems like too potent a med for this.