I'm sorry you are having these problems with cholesterol. Maybe your doctor should try a different medication....another statin drug. I take simvistatin (Zocor) and have had no problems. I don't have cholesterol problems but my doctor wants my levels extremely low because I'm diabetic and am more prone to heart attack and stroke. I've heard these statin drugs are actually very good and help you in many ways.
I have a friend whose cholesterol and triglycerides are totally out of control. I know her triglycerides are over 700. She has been this way for years, even though she has taken medication. She is now 75 years old and can run circles around me. So, yes, I do think her problem is genetic and yours could be too.
As far as the kidney function goes, it might go back to normal if it was caused by that medication you were taking. I was taking a med for diabetes and it did a number on my kidney function...bad enough that a doctor didn't want me to go on a trip I had planned! Once I was taken off the medication, my kidney function went back to normal so try not to worry about it. It's good your doctor knows about it because he/she will be closely following that.
I hope everything gets back to "normal" with your blood work.
Sherrine