There are two kinds of carnitine used by statin damaged people, they are Lcarnitine, and Acetyl L carnitine. Many find it doesn't make much difference which you take, I have seen it suggested that for nerve and brain problems, Acetyl is better, while for muscle wastage plain L carnitine is the one I prefer.
I suggest you take whichever you can most easily obtain, capsules are better than tablets, which don't work for me. The correct dose for you is something you have to experiment to find out. A good start would be one 500mg capsule a day, first thing in the morning 1/2 hour before food, if you can manage it, for three or four days, then increase to two tablets a day for another 3 or 4 days and so on until you get sufficient relief, or your bowels object by becoming loose, when you should go back one stage. This is unlikely to occur at less than 2 or 3 grams a day. some find it best to take a high dose in stages at different times, but try to keep 2 hours after food, and 1/2 hour before food to gain the best effect. It is not cheap, and there is no point in taking more than you need, it only goes to waste.
If you find the website *www.neuro.wustl.edu/neuromuscular and in the index find Carnitine disorders, well down on the page you will see Multiple Acyl CoA-----MADD with carnitine and Q10 as treatments..Coenzyme Q10 deficiency, and lipid lowering will also bring up authentic university info to show your doctor, if he is a helpful one