fastest way to fix a collapsing knee?

hi, white 19F, 5’10 and 160lbs. hate to ask this question because it’s pretty obvious what i should be doing, which is resting. i’m running in a charity event in the honor of my friend who passed from cancer and was equally passionate about running as i was. the course itself is 5 miles but unfortunately my knee keeps collapsing and is in aggravating pain whenever i stand, walk, run, etc. the family of my friend is heavily counting on me to show up and participate because of how close we were, and i absolutely want to run just as much. i know it’s stupid to ask but what’s the fastest way you guys have gotten to fix, or at least minimize aggravating knee pain from excessive running? i’m taking ibuprofen and Tylenol and even using a lidocaine stick but it’s just painful. i know i should call out but it’s not an option given the circumstances, especially because i want to honor my friend.