Unfortunately, your time to bring a lawsuit has probably expired. The statute of limitations in Virginia for medical malpractice is 2 years (my understanding). Some states have latent discovery rules; candidly not sure about Virginia. My best advise is to contact a local attorney asap. He/she can give you better direction. Search Avvo, AAJ, call your State's trial lawyers association, ask someone you trust and respect for referral(s).
Should your time to investigate a potential claim exist, interview several attorneys and hire the one you are most comfortable with and confident in.
As to potential malpractice, a defense is this was an accepted risk of the procedure. It gets much more complicated from here. Sorry for your plight.
Please find the time to watch this documentary - http://hotcoffeethemovie.com/ - it is a real opener.
This short video will help you a bit with the statute of limitations issue. Each case is different. This type of case (failed back surgery) is among the most difficult medical malpractice type of case.
To supplemen the fine answers by the other two attorneys who have posted - failed back surgery cases are almost impossible to win for several reasons. First, studies prove that about 25% of first back surgeries fail for one reason or another. There are a lot of reasons why back surgeries can fail besides malpractice and isolating a specific reason is often impossible. You saw some of that in your case, there was a question whether pain was from back or SI joint. It can be hard to tell. Second, one reason back surgeries sometimes fail down the line is that the back is reinjured. It doesn't take much to injure a disc, especially one that was already degenerated. Third, back surgeries can fail because the patient has an underling problem such as obesity and/or arthritis or a post operative infection. Here is more bad news. The failure rate goes up with each surgery on the back.
Sign up to receive a 3-part series of useful information and advice about personal injury law.