For now, call either one of the credit agencies to place an initial fraud alert for 3 months. What this will do is that if someone happens to apply for a credit card under your social, they would have to call you to confirm. Also they'll try to screen things. But as to the extend how much they'll do, it's hard to tell.
You may want to consider a full package that you pay roughly $10 a month to monitor your report. That for sure will call and alert you if anyone uses your social to open any accounts or so. One alert on an agency will automatically apply for other agencies (Experian, Equifax, and TransUnion)
After that, depending on the situtation, worse comes worse, apply for a new social.
Yep, this is coming from someone who's a victim of ID theft.