Hello, with reference to your query regarding hurting your middle of your chest for a week and half but does not hurt when you breathe but hurts when you move your arm in certain ways and there is no visible bruise or anything. In view of this we have to ascertain first whether it is a minor or a serious injury. It is always better to rule out that the pain or the heart causes uneasiness or not. If the cardiovascular system is ok, then you concentrate on your chest whether any bone or muscle involved or any other organ is involved like liver, spleen, kidney or trachea. If there is blow to the sternum that is the center part of the chest, it may injure lungs, heart or large blood vessels or esophagus. If there is less injury, there may be pain in the chest wall, or during movement of the shoulder, arm, the rib cage or the trunk of the body. Even a minor injury can cause chest pain or discomfort for days after the injury. Deep breathing, coughing or sneezing can increase the pain or by pressing down or lying on the injured area. Home treatment can relieve the pain and discomfort. An injury to the chest may break or crack a rib or injure the cartilage of the rib cage. Hence you may have severe chest pain or the pain that get worse when you breathe or cough or gets worse when you press or lie on the injured area. So it is better to do a proper physical examination, chest, X ray, computed tomography [if necessary]. Treatment depends on the underlying cause and use of mild to moderate painkillers. If there is any pulmonary contusion, positive pressure ventilation may be required. If there is any rib fracture, chest tube insertion, external fixation and stabilization that are common in large chest wall injuries otherwise positive pressure ventilation, hence it depends on the type of injury.  Anyhow you better see a physician and gets assessed what exactly is troubling you and seek remedy according to that. Thank you.