I have taken lipitor for 3 months and developed severe arm pain and weakness on exertion. Everytime I remove my shirt I have this sharp acute pain in my shoulder. I cannot fully extend my arm and wake in the middle of the night with crippling pain on the right arm. Today I look up google and realise Lipitor could be causing all this. I will call up my doctor tomorrow and get off Lipitor before I become a total cripple.