Is a signed notarized affidavit considered a binding legal document?

My husband and I are struggling with some recent changes to my step-sons living arrangements and are not sure what to do. Background:2007 - A judgment was rendered with the court (child custody/child support/visitation, etc...) At this time both (unmarried parents were living within Livingston Parish)2009 - The mother moves to Lafayette Parish with the minor child; papers are not amended.2010 - Both parties of the minor child agreed that the father would become domiciliary parent and the child remain with him. Visitation was agreed upon and further child support on the father's behalf was dropped; it was also agreed that the mother would not be responsible any child support payment.2014 (Aug) - The minor child decided that he wanted to move back with his bio mother. Papers were not changed since, this was thought to be temporary, perhaps a couple of months. The father now finds himself in an awful predicament with the mother refusing to meet to exchange the child for visitation, constant arguments, etc. The father has made several attempts to communicate with his son but has not been successful. The minor child has completely changed his behavior. I fear that child alienation may be apparent given the recent events that have transpired. Additionally, we have reached out to the school to be informed regarding academics, discipline, etc. and have not had any success. There is an excessive absenteeism problem as well as 2 disciplinary actions thus far. The concern has heightened and we are looking for some guidance on how to handle this at this time. In an attempt to keep it short, there may be questions.