Custody

I was wondering if anyone could give me an information in reagrds to a custody matter. My ex and I divorced 2 years ago and mutually agreed that we have joint custody of my 12 year old. He having physical custody.This was all done in the ststae of North Carolina.He has since moved To Virginia and I South Carolina. He decided that he didnt want my son to live with him any longer and I at the time was living in a place to small for him to stay due to the fact that my other son was living with me.So we agreed that my mom who lives in Nh would take him for the school year until I got a bigger place.Things have changed and my mom is no longer able to care for him so I need to gain physical custoy of him. She has permanent guardianship of him currently. The stae of NH said that all she has to do on her end is terminate that and her legal obligation of guardianship is done.My question is now that I live out of state in SC and my ex in Virgina.How do we go about petioning the court to reverse the physical custody of my 12 to me instead of my ex.Do I have to file a whole new custody case in NC or is there a way to adjust the custody decesion without the two of us having to do to court in NC ?

I believe you can have an attorney draft a consent order or parenting plan and have the judge sign off on it.