You should be straight with your doc. I don't know if Crestor is particularly hard on the liver, but you should ask him before taking it while your on gear. I assume you had a full blood work-up and liver function tests, as well??
Within 2-3 weeks, 'roids will raise your total cholesterol, while lowering the "good" HDL levels and skewing the HDL to LDL ratio. It will also typically raise your triglyceride levels into the high range, likewise with hemocrit/hemoglobin levels.
I was straight with my doc and when I told him what I gear I did and what I took in an effort to minimize the side effects, he agreed with me.
No alcohol intake (other than perhaps ONE glass of red wine now and then)
Take supplements of Glutathione and Milk Thistle
Limit cholesterol intake (obvious)
Take 1/2 to 1 full aspirin per day, depending on your bodyweight and whether your stomach can take it.
Make sure there is a period of MONTHS (not weeks) that you are completely OFF gear. The body is very resilient, especially the liver, and needs time to restore itself and normalize levels.
Just my $.02...