mystery injury

About eight years ago I was about half an hour into a run having warmed up well in a hot country although on very hard ground. Running down a gentle hill I suddenly felt an intense pain which developed into excruciating pain after three or four more strides. I was forced to stop. The pain was on my left outer leg parallel with my knee. There was no pain in the knee itself. I have had so many different treatments and opinions about what it may be and I have not been able to run since that day for more than ten minutes on the road or twenty on a running mill. I cycle everyday and feel no pain, I walk and feel no pain. Yet even now if I press in a specific area it is very tender although there is no swelling. I have never had a muscle xray as doctors wont refer me so I don't know what damage I have. A chirporator thought the tendon that runs down the side of my leg may be in spasm and massaged me in the area. This was very painful and there was no improvement after several sessions. I have had acupuncture as well to no avail. Does anybody have any suggestions for treatment? Prior to this I never had any running pain or injuries. I would love to run again.

Its obvious.

Its a problem with the lateral (outer) knee ligament.

These can be very painful in a localised spot. Take ages to heal due to a poor blood supply. Can be a surgery job.

Eight years! 

8 years is a long time!      I doubt its Lateral Collatarel Ligament unless your pain came on after twisting your knee whilst falling/running...?   Also you'd probably feel it when walking and cycling and as soon as you start running - not 10mins into a run.  And it should have healed well before now...

I'd agree with chiropractor about the ITB down side of your leg - it could be tightening up and pinching a nerve possibly... BUT only when running.    Question is WHY it tighetening up??   Painful deep tissue massage down side of leg may temporarily give relief, but is obviously only addressing a symptom and not the cause.   A sports physio could try mobilising bones of the feet, fibula, SI joint and/or lumber spine.   Anyone of these joints could be out of place.  I'd also make sure Gluts (on both sides) and hamstrings are loose and 'firing' properly... 

Ok thank you for the advice, I guess the mystery remains, I have no problems with feet spine knees or major gluts, I am active and feel on good form except for this one tiny point which is as painful today after a short run as it was the first time it happened. Would an xray which shows muscle be any good, and is this something that sports physios can do or just doctors?

Ultrasound or MRI scan would be needed to check the soft tisuue.  On NHS you'll need GPs referral - you need to over-emphasis to him/her how debilatating it is for you, otherwise he may not refer you... Some GPs don't seem to realise how much running means to someone quality of life!   If not, you'd have to go down the private physio - consultant route...

All that said, just because the pain is at the knee doesn't mean the cause is in the knee.  Don't be surprised if you had a MRI on the knee and everything come back normal!  From your symptoms I'd still suspect a biomechnical compensation that is over-stressing the knee joint at THAT point when running.  You should get your running gait properly checked.