<s>[INST] Yesterday for no reason, my right knee gave out, where lower bone meet the knee joint. I did not fall, but my leg was weak and pain radiated down to my ankle. It doesn t feel like the joint, more like my lower leg is being twisted, but it isn t. Last week I got sunburned on my legs and feet. I have changed shoes but that didn t help. I have had tick bites but not noticed any bulls eyes, infections or rashes. Ive had low grade fever of and on, and at times my breathing is shallow. weird!! Ive also had an allergic reaction to the rubber in some Tommy Copper knee wraps I have to wear at work and the elastic in my sock. And ive had an allergic reaction to some laundry detergent. That was last week, but I randomly run across something washed in it, and I have allergies like never before. [/INST] Hi, You may have knee instability due to rupture of knee ligaments mostly anterior cruciate ligament. Minor twisting in just may be reason for rupture which may be unnoticed. Diagnosis needs to be confirmed by doing MRI of the involved knee. Meanwhile wear long knee extension brace while walking. Visit to orthopedic surgeon for detailed clinical Examination is recommended. Hope I have answered your query. Let me know if I can assist you further. Regards, Dr. Jayesh Vaza, Orthopaedic Surgeon </s>