Ok.. this sounds like a "Hard Money" type of loan. Marquislending.com is probably the best place to start. The interest rates suck pretty bad though.
I would probably work out a deal with your brother and have him "Owner Finance" the $50,000 and you can just make payments to him. You can file the note at the courthouse, and as soon as you get your scores back up, and everything is looking up again... refinance and pay the note off.
If that is not an option, a hard money loan will work, but you will want to pay that off as fast as you possibly can as hard money loans are a bit ugly.
I hope that helps.
Jason C Campbell
Option One Real Estate
Platinum Top 50 Finalist