knee pop / twinge but no real pain

Question
I starting running / training last august for a half marathon and completed it in October. Everything went well and i really slowed my running until Feb and have picked have started running about 18 - 20 miles a week. Two weeks ago I ran 13.25 miles in 1hr 50 minutes. Everything felt good and felt fine the next day. I have now noticed a slight pop / twinge in my knee (would say below/behind knee cap), but it does not hurt and it may not happen for 10 strides but then may happen for 5 strides in a row. I am not sure if I am reproducing the same issue, but if I stand in place (not during a run) and take my knee back past 90 degrees and put it down my knee will pop (i can hear it). If I take my knee back and pause with it back it does not pop when i put it down.

Answer
Hi Rob
Without knowing your bio and past and present fitness level and your training,i would say you have some real serious tracking and alignment problems which are the pre curser to Chondromalacia.It doesn't seem acute,but i would treat it as a very serious injury because if you don't it WILL BE.The best tool for your situation is a stationary bike for 40 min 4 times a week with med tension and high rpm 90rpm.I would not run for 30days until you get some proper tracking and alignment back and then do a little test run and then make a evaluation of how you feel.For your info this is very commom but can put you down for a long time if you don't take it serious and correct the problem.I know personally,down 8 months and now a expert and how to correct it and have helped many many athletes.Any other questions just get in touch Rob.

All the best

John