Am Suffering From Sever Cramp And Burning Sensation From Buttock

Am suffering from sever cramp and burning sensation from buttock downward right till my ankle on backside of both my legs this happen when I stand for only 5min or walk a few yard the pain become so unbearable that I have to immd sit down even if its on the road and shake my legs for sometime and immd the pain stop but comes back again when I start walking a few yards.
Am not diabetic, male, 5.11 with a weight of 74kgs, have hypertension and on medication, everyday I do a 8km walk but with the above problem now days every 500mts I have to stop for sometime and stretch and then continue to complete the my morning 8kms.
Visited the Doctor yesterday and he prescribe nurokind lc one tab per day, I have still not started on it just wanted to now if it is safe and will it help my case. I dont want to doubt my doctor but when I visited him yesterday he was so busy that I felt he did not hear me out properly.