I have been taking lipitor for about 4 years now, without any sid...

I have been taking lipitor for about 4 years now, without any side effect until the doctor put me on 40mg of lipitor. Now I have leg pain all the time, sometime so bad I can't hardly walk. I seen two doctors and had about every test you can have.Mri/scans/exrays also. they have found nothing,I have ask both doctors if the lipitor it was lipitor. I just can't believe I walk 3 to 4 miles every day before I was change to 40mg of, now I can't even walk out to get the mail.