Disability Back-Pay withheld for child support even though the support has been paid and I am not behind in my payments?

I recently received a lump sum payment for disability back-pay. Almost 75% of the this payment was withheld because of court ordered child support. However, I sacrificed in all areas of my life to make sure that my child support was duly paid. I am not behind on my support payments, and am left wondering if I will be awarded the money that was erroneously withheld? I will have the child support deducted from my monthly disability check going forward, but that has nothing to do with my lump sum payment. Also, I did not have the support lowered even though I was no longer able to work. I used half of my VA disability check each month to pay the child support because I knew it was the right thing to do and, more importantly, because my son means the world to me.