I have a son that I am paying child support for and the mother has just moved and will not tell me her new address...can she do this? Also I recently had an operation on my eyes and I have not been able to work, how can I get the child support modified. I cannot afford $600.00 per month for 1 child since I no longer have a job.

I have a son that I am paying child support for and the mother has just moved and will not tell me her new address...can she do this? Also I recently had an operation on my eyes and I have not been able to work, how can I get the child support modified. I cannot afford $600.00 per month for 1 child since I no longer have a job.
You need to file to modify the CS order ASAP. Since you have medical reasons the court will almost certainly lower the amount on a temp. basis until you are well enough to return to work.

Is there anything in the court order that states that parents are to keep the court and each other notified of address? If there is you can file for contempt since ex moved.

Can I file or do I have to pay another attorney

You can file pro se (without an atty) but it may be worth it to pay the atty to do it for you. Everything must be filed to exacting standards and specifics. If you miss one step, the whole case can be dismissed before being heard. You need to get this done NOW. Contact the NC bar association in your county to find out who is on rotation for pro bono or reduced fee work.