I really hope you can help with this one.

I recently started running from January this year, gradually building up to compete in 10k races in the summer.

Almost 8 weeks ago now whilst running one of my mid week 5k runs, I experienced a rapidly growing sharp pain to the left hand side of my left knee after about 3k which forced me to limp back the remaining 2k. The initial injury seemed to come from nowhere.

I did not run for 3 weeks after that to give what ever injury I recieved a chance to recover.

On week 4 I went out again for a short run, about 1k with no sign of the previous injury which I was delighted about.

For my next run I increased the distance and by the 2k mark the pain returned to my left knee area, forcing me to stop any running, although I could still put weight on the knee without any great pain.

This has really got me down as I love my running, what do you think the problem could be?