I'm sorry to hear about your right knee pain and swelling in your left leg and foot. These symptoms can be concerning, especially if swelling is involved, as it might indicate inflammation, injury, or possibly issues related to blood flow such as blood clots.

Given the swelling in your leg and foot, one important condition to consider is deep vein thrombosis (DVT), which is a blood clot in the deep veins of the leg. This condition can cause pain, swelling, and requires prompt medical evaluation. The medication Rivaban (Rivaroxaban) you mentioned is an anticoagulant (blood thinner) commonly used to prevent and treat such blood clots.

What you should do:

• Seek evaluation by a specialist doctor, preferably a vascular specialist or an orthopedic doctor, to assess your knee pain and leg swelling.
• If you experience sudden shortness of breath, chest pain, or worsening leg swelling, seek emergency medical care immediately as these could be signs of a serious complication like a pulmonary embolism.
• Avoid prolonged immobility and keep your legs elevated when possible to reduce swelling.
• Follow any prescribed medication instructions carefully and inform your doctor about all symptoms.

Prompt medical assessment is important to determine the cause and appropriate treatment for your symptoms. Please consult a doctor as soon as possible for a thorough examination and management.To narrow down potential causes, we will need some more information.I understand you're having right knee pain and swelling in your left leg and foot. Could you please share your age and gender?