For those who've had overuse knee injuries: looking back, what was actually happening in the weeks before it hit?

Currently recovering from patellofemoral pain (runner's knee), 6 weeks in. Doing physio, taking it slow.

But I keep going back trying to figure out exactly when things went wrong. My training log looks fine — mileage was controlled, I wasn't doing anything crazy. I felt okay. My watch said my training load was "productive."

And yet here I am.

For people who've been through this — when you really analyze what happened, was it a specific run that did it? A surface change? Fatigue you didn't recognize? And do you think you could have caught it earlier if you had different information?