What kind of side effects is your relative having?
You are correct, simvastatin and Zocor are the same product, but generics are not always the same as the branded medication.
Here are a few suggestions:
search the package insert for common side effects. This is the medical document approved by the FDA. The information is in section 6.1 under Adverse Reactions: http://www.merck.com/product/usa/pi_circulars/z/zocor/zoc...
Call their doctor or pharmacist to see if this is a common side effect or perhaps from something else.
Visit the FDA's website and search for simvistatin under "Drugs" (FDA.gov)
If you can provide a little more information, I may be able to help. My husband is a representative for another cholesterol medication and may know the side effect profile well (sometimes side effects are specific to the medication or may be related to all the drugs in the class)