Pain in right knee &ankle. I mri test?

I started feeling pain in my right leg since after I increased my per day walking distance from 0.5 km to 2 km. i started feeling pain in my lower side of right leg muscles. Also, I realized that the was some knee injury caused by the placement of an iron road under my desk in office. I almost completely recovered from that by ensuring not to let my leg touch the iron road & by applying Volini in the affected area of knee. But problem caused by excessive walking is still there & all the time I feel heaviness in my right leg alongwith some pain while stretching or folding my leg. Is this really due to vitamin D insufficiency as told to me by a doctor or should I go for MRI test? because if it is vit D insufficiency why it has only impacted my right leg instead of whole body. If it is really vit D problem, is it prudent to take injection or not? or should I MRI test? period of pain - 1 month approx & vitamin d related medication - 1 week complete