Help me save my house!

My name is Dustin Garner.  I am a disabled Army combat veteran.  I purchased my house in 2012 and now own it free and clear.  However when I purchased it the property had already fallen into a tax sale for unpaid back taxes.  The title company and the county did not notify me of this,  Nebraska has a property tax exemption for disabled veterans but I filed the paperwork incorrectly the first two years I was here.   I was then informed that if I do not pay the full amount of back taxes $5500 dollars within the next two months the county will auction  my home off.    They want this as a one time payment and will not accept an extend payment plan.  I am living here with my two daughters soley on my fixed disability benefits and can not afford such a large payment.  I have tried getting a loan, and talked with different charity organizations to no avail.  I need help or my daughters and I are going to lose our home.