> Look at every part of basement if any leakages or tore happened into the sewage flooring.. whether it’s wooden or cement. Look carefully at the corners of the basement.
> Try to pore excessive water with full force at once, which will clean any dirt or choke that would have happened in drainage.
> Check your sump pump, whether it is leak or required replacement or repair.
> or maybe look in for any stuff or dead rats, fungus or any sort of those things being decaying in some part of your basement in or nearby sewage drain system.

My cousin faced similar problem and tried above steps and he was successful in solving it through.
or else you can contact the home owner and if you have made a contract and in written at the time of rent, ask them to repair or cleanup the basement and places in and around sewage and sump pump.

Please let me know if you need any further help. I would be happy to help you.

Good Luck.