Who is your IVA with? How much is the debt and I hope it was a debt collector rather than a bailiff and you didn't let them in your house.
You need to speak with your IP tomorrow first thing.
Sharing from experiences of dealing with debt
The greatness of a man is not in how much wealth he acquires, but in his integrity and his ability to affect those around him positively.
Bob Marley. http://kallis3.blogs.iva.co.uk
It is possible, depending upon the circumstances and the relative amounts, to add a forgotten debt to an IVA -- you will need to speak to your IP asap to discuss this. In the meantime do not allow the bailiff entry to your home and make sure all doors are locked and windows closed, when not in use.
My opinions are merely that .. opinions based on experience. Always seek professional advice.
IVA Completed 23rd July 2013 .... C.C. 10th January 2014 http://foggy.blogs.iva.co.uk