left leg pain during running

[whistler]

hi, during early 2000 whilst racing (13 mile off road) i landed very healiy on my left leg, within minutes i felt some mild discomfort, i thought i my have tweaked a hamstring or lower calf and continued to finish the race, i rested for three days before resuming light training,i noticed that whenever i ran up hills or started to up my tempo my left leg would feel tight after running for a few minutes, to the point where i had to stop and rest, it felt like at the top of my leg ,it had an elastic band constricting the blood flow ,i have been to two physio's and they were treating me ,thinking it was piriformis syndrome. the third physio put me on a tread mill and told me to recreate my problem, then checked my blood pressure at my ankle, he said it was very low and referred me to a consultant. the consultant thougth i may have a kink in my artery at my groin area (common in cyclist) , after going in hospital to have a dye injected and xrays they found no problem with blood flow, i am now waiting for my next consultation, i still run but only at very low intensity, i need some idea's to bottom this problem ,it's been six frustrating years