What Causes Weakness In Arm And Leg Muscles While On Simvastatin?

I have significant weakness in my arm and leg muscles which has gradually gotten worse in recent years. I have been taking statin drugs since 2006. I was on Crestor for several years and am now taking just 20 mg of Simvastatin/day. Could this be my problem and, if so, what should I do? The research I have done suggests that I could take a daily dose of 800 mcg of folic acid, 200 mg of B6 and 1000 mcg of B12 sublingual instead of statin drugs. I am under the care of a cardiologist. I eat a healthy diet, take very brisk walks every day and am asymtomatic. Thanks for your opinion.