You don’t always need to see a doctor for knee pain; however, an ultrasound is nevertheless still the best way to diagnose your condition. You should visit your doctor and consider an ultrasound scan if you have: Stiff knee Restricted knee movement Knee swelling Weak knee Chronic knee pain Knee joint pain Visit your doctor promptly if you’re experiencing any of the following: Red knee Knee pain following an injury or accident Significant knee swelling Knee warm to the touch Knee popping or knee crunching Unable to straighten the knee Severe pain around the joint These symptoms may suggest an infection, dislocation, or fracture around the knee joint, and you shouldn’t ignore them. If your knee pain is mild, self-care at home may be enough. However, you should always visit your doctor if it doesn’t clear up with rest after a few weeks.