There is a chance that the band of tissue on the outside of your leg called your ITB and the muscles that attach into it could be involved.
What does it feel like?
Pain associated with your ITB usually presents like a sharp pain on the outside of your knee. Often, you'll be able to run for a little while and it will come on gradually. It can often get so intense that you have to stop running entirely and then even walking home will hurt.
It often comes on gradually over time or when you haven't run for a while. The most common time it becomes an issue is when you have increased your training load quickly, such as not leaving yourself enough time to properly train for an event. (Don't worry we have all been there!)
How can I sort it out?
If you think you possibly have a problem with your ITB it is best to see your remedial massage therapist or physio to have a chat to them and see if this is what is causing the pain on the outside of your leg. They can then create a plan of attack to relieve the pain and also get you back training for your event!
Depending on the severity of it there are several exercises and stretches that you can try at home that may help.