Journal 42: hitting a wall

Today was a trying day emotionally, mentally, and physically. Getting home from school close to 5pm does not leave much time for anything. I came home had about 10 minute break and had to turn around and go to classes tonight. I tried to not get in my head or let the negative thoughts take over. I am hitting a wall. I just want to relax. I took some breaths and pushed through my frustrations and tiredness. I only did 1 mile tonight and I saw a friend that I did my cool down lap with. I am still noticing pain in my left knee when I run. When do I need to be concerned about this pain?