Can I sue my landlord for back rent if he has been collecting my rent for 6 months or better and hasn't been paying his house payment?
This morning I got papers from the Sheriff's office stating the house is going up for auction in 30 days.
No, you cannot. Whether or not your landlord's obligation pays their mortgage has no effect on you; that's between them and their mortgage company. As a tenant your obligation is to your landlord. So as long as you are being provided with a place to live you must continue to meet your rent payments (i.e. you still owe your landlord rent). If you do not pay, you can actually be evicted from the premises.
The above holds try for as long as the landlord remains the legal owner of the property. Once title passes via a foreclosure sale, then your obligation to your landlord ends. However, you will then be required to pay the new owner (you will be notified).
Additionally, you should be aware that a tenant is given rights and protection if their rental unit is foreclosed upon. When a rental home goes into foreclosure, tenants who have a written lease can continue to occupy the home until the end of the lease period, or 90 days, whichever is longer. The only exception would be if the new owner intends to move in and occupy the home as their primary residence; in that case, a 90 day notice to move would apply.