I know this is everyone's favorite kind of thread - a "Predict Me/Diagnose Me/" - I'm putting my faith in you, LetsRunners!
After a long break from running, due to a cycle of injuries in a number of different areas, which always stopped me once I got going, I have been able to build back up for my best running in a long time. A couple weeks ago I did a 1hr30min long run, which was my longest so far.
I felt fine afterwards (other than just tired legs), but after a few days of rest when I tried to run, I had to stop my run after 30 minutes or so because I felt pain on the outside of my left knee/very bottom of my left quad. I have gone for a couple more runs after this (taking a few-to-several days off in between) and each time I've had to cut my run short because of this pain.
What do you think this is, and how can I fix it? This time I am determined not to let another injury derail my training. I have been free of road bumps...until now. Also posting a link to an image below showing exactly where the pain is. My finger is pointing to the sorest area (outside of the knee), with the length of the finger showing the whole pain zone.
If it means anything, although I had no pain until after this long run, my quads always felt tired when I began my run.