Shellette,
My *** doctor had me try different regiments of vitamins and supplements including Coenzyme Q-10, Creatine and Carnitine. Apparently for some MD sufferers they work. I personally did not notice any difference. I would gladly purchase $30 -$40 worth of this stuff a month if it was improving my life but nothing was happening after months of trying them. Of course nothing's going to cure the MD. These supplements supposedly help your muscles use energy more effectively. The bottom line is, it depends what kind of MD you have whether or not these things will make a difference.
As far as exercising goes, yes, you want to do LIGHT exercise. If you DO have muscular dystrophy, your body cannot replace damaged muscle cells. So you don't want to exercise until you are sore. This is the goal of a weightlifter but not us. On the other hand you do not want your muscles to atrophy, or shrink from non-use. You must find that exercise zone between damage and atrophy.
By far the biggest favor I've done for myself is to stretch. The last thing you want is uncooperative muscles. It's hard enough to move through the day without battling muscles that respond like taffy. I especially make sure I take 30-60 seconds, 3 times a day and stretch my calves. I have very weak shins resulting in foot drop. This helps a lot and prevents me from needing braces to hold up my toes.
Good luck with the biopsy. I've been through it and a couple EMGs so I can answer any questions. Again, think about contacting your local *** clinic. They have huge resources and some very compassionate people willing to help.
Mark