First off, sorry this has happened to you... if it were completely up to us, it would NEVER happen.
Unfortunately YouTube and Facebook systems are flawed in that they flag legit music use quite often. The problem is their copyright system doesn't account for legal nonexclusive use of music, so you will have to dispute their claims by contacting them and showing proof of your rights. Just send them a copy of your PDF contract you receive with every purchase.
Again we're very sorry they don't have a better system for the creative music community yet. YouTube at least has their dispute system that usually works out just fine. See: YouTube said a Copyright Claim was made for my Song but I bought my Beat! Help!