You may hire another attorney, but only an attorney licensed to practice in the bankruptcy court of your state may represent you. You can represent yourself (which would be VERY, VERY UNWISE), or you can also, in some states, pay a bankruptcy petition preparer. However, you would have to make the legal decisions, and the preparer cannot practice law and cannot assist you with choosing the correct form of the order.
An ex-parte order means that you would file a motion and proposed order with the bankruptcy court to allow the new debt. I estimate it would take about 2 or 3 hours of time, and if the attorney is charging $300 per hour, then you're looking at from $600 to $900.
As I see it, you have a couple of options: 1) Hire a different attorney who will do this for you at a lower rate. 2) wait the 2 months until the chapter 13 is completed, and then you can do the FHA loan without any need to have the bankruptcy court's permission.
For a referral to a different attorney, contact your local or state bar association.
10+ years in the legal profession.