I have had knee pain only at night when i try to lay on my side and lay the inner part of my knee on the mattress. the only way i can sleep is turning on my opposite side and keeping the painful leg off the mattress.?

Hamstring tendinitis: While there may be many causes of this pain, two very common sources is hamstring tendinitis that occurs from limping. The limping is often caused by weakness of the quad muscles, but can also be caused by knee problems such as arthritis. If you have had a fall recently, the cause can also be an mcl tear. To isolate the problem, a trip to your friendly neighborhood orthopedist may be helpful.

Many possibilities: Your pain could be as a result of many different things. A thorough history and physical exam and possibly some laboratory and radiology exams are needed to determine the exact cause. Causes of pain may include: trauma (fracture, tendon or ligamentous tear, arthritis), infection, metabolic conditions (gout), musculoskeletal or biomechanical abnormalities.