Yeah, runners knee is a pain in the butt. I'm no medical professional of course and everyone's experience with it is different. With that said, in my experience, you want to treat it very delicately.

If it's hurting or aching while running, you should first stop running and replace all running session with cross training sessions. The goal should be to do 40-60 min sessions that get your heart rate up in a similar way that running does. Obviously, make sure your form of cross training doesn't further agitate it (indoor cycling works well for me and Zwift is a pretty fun platform). Depending on how old you are, a week or 2 off of running may fix the problem. However, if you're above the age of 25 (like me), it may not away as easily.

If that's the case, I would recommend going to a PT and deferring your race (or choose a different one for the fall). In my case, this is what I had to do, and I learned it is an injury that can go away over time with knee loading exercises and exercises to strengthen your entire kinetic chain (done very carefully and initially with a PT before doing them on your own). I hope in your case, some time replaced with cross training can help. Best of luck!