I have been on Simvastatin for 11 months and have gained 46 pound...

I have been on Simvastatin for 11 months and have gained 46 pounds. I also am having problems with my knees joints and wake up 2 to 3 times a night. My Cardiologist told me weight gain is not a side effect of this drug but I'm not so sure. He also said my knee problem is a result of the weight gain. I quit smoking last September and I know that's responsible for some weight gain but not 46 pounds. I walk for half an hour every day, watch what I eat and do cardio arm and leg exercises. I also have a rash on my arm, which is says in from Plavix, and he took me off it. I had a heart attack last September. Anyone else experiencing these problems?