Miriam symptoms and conditions

I went on Simvastatin 40mgs last Christmas 2007 because of the family history of strokes, I was generally feeling very well .
Since being on statins I have felt awful , with lots of side effects " muscle cramps, upset stomach, really really tired, strange feelings in my chest and bad palpations "... I thought I was really ill.which made me very depressed.and even had test's done at the hospital to try and find what is wrong with me thankfully nothing appears to be seriously wrong" so why feel so dreadful i thought it had to be the statins!!"
I came off them my self four weeks ago ,since then I have been to see my doctor who has agreed for the time being I should be off simvastatin but consider taking a milder statin.
I do feel slightly better after four weeks ,but still get some of the side effects can any one suggest roughly how long it takes to feel like one's old self again.....Please!!!