Custody and support issues

[kubo2009]

My husband and I are in the midst of a really frustrating custody and child support battle with his ex-wife.  When my husband and his ex divorced 2 years ago, child support and custody were determined by the court in the county they lived in.  Shortly after the divorce became final, his ex took their son to Utah for a "business trip".  She never came back.  Apparently she had been planning to move there with their son, and used the business trip as an excuse to get permission to take their son.

My husband has not seen his son since then.  He has payed child support every month, based on the determination of the court during the divorce.  The problem is, the original determination was based on cost of living in Orange County, Ca.  His ex and their son have not lived in Ca. for almost 2 years; they live in Utah, where the cost of living is significantly lower.  She is also in violation of the custody/visitation agreement that was decided in court; my husband was to have shared custody of his son (every other weekend). 

Now, she has somehow found a way to come after us for back child support.  My husband's accounts were frozen, and a lien was placed on his paycheck.  She's trying to get child support for months when they were separated but not yet divorced, and there was no court order in place for support.

I don't know what to do, or where to start.  With the current state of our finances (thanks to his ex), hiring a lawyer isn't exactly possible.  Does anyone have any information or advice?

Thank you.