What Can I Do About Unpaid Child Support ?

In 2006 my ex was ordered to pay $500/mo child support. In 2008, he switched jobs, started making less and filed to modify the CS. On his own he started paying $250/mo. His petition to modify was dismissed (his attny failed to follow up). My ex is now working for cash and paying the same $250/mo. There's nothing to show for his income or assets.
For the last year, while his petition was pending, he ows me $2500 in unpaid child support and $2500 in attorney's fees.
My questions are:
1. can I get the $2500 I had to pay to my attny from my ex?
2. do I need to hire an attny to get the $5000 from him or can I go through some state agencies (I'm really not rich) or can I do it myself?
3.is there a minimum child support amount that must be paid even if he has no provable income?
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