Suggest Treatment For Constant Knee Pain

Hello, I have left leg medial knee pain. I press on the inside joint area and there is sharp pain. I can walk, go up and down the stairs, bike without pain. If I cross my legs and push the left leg down it hurts. There is pain in my left hip joint that radiates around up to my lower back. The consistent knee pain started about 6 months ago. I am 5'4 and weigh 140pd. Thank you for your help