It looks like the landlord was not completely honest to you. First step you should do is to call him to get more information. You need to start looking for a new property, since after the auction date the property will no longer belong to your current landlord.
Most probably you have a security deposit or paid for the last month in advance, discuss using that as September's payment with your landlord. When you leave keep the property in good condition so the landlord can return you the rest of the deposit and to help with the foreclosure sale.
I would be prepared to pay your rent however you need to know that you will be recieving your deposit back . Negotiate with the leasing company and let them know what just happened. They may not even know. You also need to protect your credit so make sure you have all the facts and get everything documented.. Leave the home in good condition!
Feel free to contact me if you have any questions!