Discouraging run last night - started off at a pace I thought I could sustain, but I got eaten alive. Meant to go 5 miles but had to shut it down early, something I hadn't done before. Hot and humid weather. During the last mile, I accidentally cut someone off and got cussed out. Not my night.

Most concerning, though, was some pain I started having in my right knee near the end of the run - it's a fairly deep, sharp pain below the kneecap. I've had some soreness in this area of both my knees *after* running, but this was the first time I experienced it during a run. It hurt for another hour after my run, and when I woke up this morning, my other knee was hurting in the same spot. Not a good sign.
Googling around, it looks like this a pretty common ailment for runners, but there are a variety of possible causes such as poor form, weakness in the quads/hips/core, etc. Have any of you dealt with this, and what did you do to fix it? Any recommendations? I do think my form could use some work, as I might be overextending my legs a bit.
I'm guessing the correct thing to do would be to stop running until I get the problem diagnosed/fixed, since I don't want to permanently damage my knees by trying to push through it. On the other hand, I only have an easy 4-miler scheduled for tonight, so part of me wants to try it out, see how I'm feeling, and use it as an opportunity to work on my form. I was expecting to deal with some injuries at some point, but it's disappointing that I'm already having issues after just one month of training.