It doesn't (as far as I can tell) cause an actual autoimmune disease. It can cause Lupus-like symptoms. Look up "Drug-induced Lupus" for a better understanding of what I mean. The symptoms usually abate over a period of time once the drug is completely out of your system.

Is there a known link between zocor and autoimmune disease?

Thank you sooo much for giving me a direction.  I am very scared.

You have to look at two possibilities here, Myositis, and Myopathy. The symptoms are very similar, but Myositis is autoimmune, and Myopathy is neurological. The rheumatologist should run a full autoimmune panel including SED-rate. This should indicate whether or not you have an autoimmune reaction going on. If not, then hurry up to the Neurologist. In fact, if you think it may take a long time to get the appointment with the Neuro. get the referral now, and make the appt. right away. You can always cancell if you don't need to go. You need to get an EMG. This measures electrical activity in your muscles. You will also need your blood potassium level checked, and may need a muscle biopsy to confirm the diagnosis. hopefully, it will be reversible. Here are some links that iI hope will help. Good luck.

You may have looked at this 1st link already, but read it carefully again.
http://www.zocor.com/simvastatin/zocor/consumer/product_information/ppi/precautions.jsp

This one refers to the muscle wasting as Myopathy, and also has a quick list of all the drugs not to take with Zocor.
http://www.zocor.com/simvastatin/zocor/consumer/product_information/ppi/precautions.jsp

This link, if you look at the last section labeled "Hypersensitivity (Allergic) Reactions" It says that Zocor can cause a reaction that mimics Lupus, which like Myositis, is an autoimmune reaction.
http://www.zocor.com/simvastatin/zocor/consumer/product_information/ppi/side_effects.jsp

This link talks about Myopathy.
http://www.neurologychannel.com/myopathies/