Hello Dear. There are several conditions which might cause knee locking and pain. There are two types. true locking and pseudo locking. True locking is caused due to meniscal tear of knee joint, or some foreign body stuck in knee joint. There ll be severe pain and it has to be corrected by surgery. Pseudo locking is caused by Swelling around knee joint due to any infection or conditions like rheumatoid arthritis, gout etc May be you had a sprain and sustained a mild injury in the knee joint causing inflammation and pseudo-locking. I suggest you to consult an orthopedic surgeon who will treat you with pain killers, ice therapy and knee joint strengthening exercises Hope i have answered your question. Feel free to contact me if you have any more questions. I ll be glad to help you. All the best With warm regards Dr Sanjay Kini