Hi.. Welcome to HEALTHCARE MAGIC.. I have gone through your query and can understand your concerns.. As per your complain as you have fallen from stairs leading to landing on the right knee and in case if you are able to put weight over your leg while walking then one thing is clear that there does not seems to be bony fracture and is most probably soft tissue injury.. The swelling can be due to accumulation of inflammatory fluid at the injury site due to soft tissue inflammation secondary to injury.. Other causes of severe pain and discomfort can be due to injury to Anterior Cruciate ligament [ACL injury] or Meniscus tear.. I would suggest you to consult an Orthopedician and get evaluated and a thorough clinical evaluation and x ray as well as MRI can help in diagnosis and treatment can be planned accordingly.. In case soft tissue injury without any tear of meniscus or ligaments you can be advised to continue taking anti-inflammatory painkillers like Ibuprofen or Naproxen, continue icing and elevation and limit movement.. In case if there is meniscus or ligament tear you can be advised to apply an analgesic ointment and brace it with a knee cap or crape bandage.. In case of fractures or extensive wear and tear immobilization by placing a cast can help.. Hope this information helps.. Thanks and regards. Dr.Honey Nandwani Arora.