Knee cap pain

Ever since I ran the half marathon about a week ago, I have been experiencing wierd knee pain in my left knee. I didn’t feel any pain during the race, but later that night. When I would walk, I would feel the pain as I lifted the leg, I would feel the pain above the knee cap. I iced it, and took ibuprofen.
I have done a few runs since then, and they have mostly gone okay. I would stretch out before the run. Then I would do an easy warmup. Then following the run, I would ice the knee and take ibuprofen. I was scheduled for an 8 mile run on Saturday. I did a 10 minute warmup, then started the main run. I did about 1.5 miles, but the knee was uncomfortable, so I stopped the run.
But the pain seems to come and go. At times, the knee feels normal, and at other times, I start to feel the discomfort. The pain is more like a light to sometimes strong discomfort. And it has moved around. Initially it was on the top of the knee. Sometimes it is on the inside of the knee. At one point it felt like it was on the corner of the knee cap itself, like a bruise.
I have a full marathon next weekend. So I am trying to rest my knee. I am scheduled for a 30 minute jog tomorrow night, but I am going to skip it. My next main run is for Wednesday, which is for 4 miles at race pace. I will see how my knee feels at that point.