I underwent a second ACL reconstruction about 16 Months ago. Today on my run I felt my knee pop, to which it did not click back in place until I sat down to extend it fully. It's not really swollen, though there is a slight puffiness and while the pain is nothing like my initial two injuries, there is a bruise-like pain and discomfort on the inside portion of the knee, specifically when walking and worse if I ascend stairs. Coming off of 2 years unable to enjoy athletics, I am wondering if this is a pain I should be overly concerned with or potentially only a scare after all that my knee has been through.