Did i tear something in my knee?

[JennyD419]

Hello All,
Two weeks ago while running, my left knee seemed like it shifted inward and gave out. This is happened at least 5 times before but never while i was running. When it happens, it is extremely painful. It had swelled up right away and the top of my knee was stiff for a day or two. When this has happened in the past, the stiffness and swelling has gone away after a week.
This time around, i have been having a very sharp pain under my knee, inside the knee cap and on the side of my knee (laterally) Its like its locking, catching and occurs mostly when i walk, i cannot straighten the knee fully. It also happens either after walking awhile like 5-10 miniutes or right away. Sometimes i dont have a pain occurrence at all until the end of the day after overuse.
Did I tear something this time hurting my knee? I have a race in less than a month and am hoping i can run it.
Thank you kindly for all your help and feedback