Hi Mohan:

Your doctor got it right this time.Vitamin D3 50,000 IU for12 weeks, then take one every month--it will bring your level up.
But please make sure to check your D3 level at least twice a year. Consult your doctor to take chelated magnesium for a while, also. This is necessary when you take D3, and many people are deficient in magnesium anyway. Eat considerable quantities of lettuce for vitamin K, which also is necessary when you take D3.

It takes right dosage, and time in order to get your D3 level to an acceptable level.

Ali