Bruising/discoloration, guarding joint (opposite of favor, so can't exist together) with joint instability are consistent with acute meniscal tear (ACL) tear, acute or chronic shoulder dislocations, post any joint dislocation. Call you doctor.
While the list below can be considered as a guide to educate yourself about these conditions, this is not a substitute for a diagnosis from a health care provider. There are many other medical conditions that also can be associated with your symptoms and signs. Here are a number of those from MedicineNet:
A bruise, or contusion, is caused when blood vessels are damaged or broken as the result of a blow to the skin. The raised area of a bump or bruise results from blood leaking from these injured blood vessels into the tissues as well as from the body's response to the injury. Treatments include applying an ice pack and pressure to the area by hand.
A hematoma is a collection of blood that is outside a blood vessel. There are different areas where hematomas occur including; inside the skull, on the scalp, ears, septum, bones, finger nails, toe nails, and intra-abdominal.
Osteoarthritis is a type of arthritis caused by inflammation, breakdown, and eventual loss of cartilage in the joints. Also known as degenerative arthritis, osteoarthritis can be caused by aging, heredity, and injury from trauma or disease.
The anterior cruciate ligament helps to prevent the top and bottom of the knee from sliding back and forth. Symptoms and signs of a torn ACL include knee pain and swelling. Treatment of a torn ACL depends upon the health of the patient and the patient's expectations and willingness to undertake extensive physical therapy. Rehabilitation after surgical repair of an ACL tear may take more than nine months.
At MedicineNet, we believe it is important to take charge of your health through measures such as a living healthy lifestyle, practicing preventative medicine, following a nutrition plan, and getting regular exercise. Understanding your symptoms and signs and educating yourself about health conditions are also a part of living your healthiest life. The links above will provide you with more detailed information on these medical conditions to help you inform yourself about the causes and available treatments for these conditions.