Now I am not sure what he means by “many different variations”. You want to take D3 which is also called cholecalciferol. It comes in many different “strengths” and Biotech even makes one with 50,000 iu in a capsule.
If you or he have not already read on this website “About Vitamin D” I highly recommend you do so. Pay close attention within this to http://www.vitamindcouncil.org/about-vitamin-d/vitamin-d-and-other-vitamins-and-minerals/. It is very important!
The VDC recommends 5000 iu a day and the safe upper limit level is 10,000 iu a day. We recommend testing blood levels and trying to reach at a minimum 50ng/ml or above. The top end of the range is 100ng/ml.
I believe there is a doctor in South America that is using upwards of 40,000 iu a day to help MS patients. Higher amounts of vitamin D may need to be taken if you are already in a diseased state. Everyone in your family should take some, not just you! If taking high amounts worries you (over 10,000 iu), I would then recommend a full spectrum sunlamp/bed. MS they are finding is caused by a lack of Vitamin D.
You may also like to read http://www.vitamindcouncil.org/health-conditions/multiple-sclerosis/
Any more questions, just ask!