You need to contact an attorney. There is a risk of exposure to communicable diseases such as Hepatitis. Even if everything is cleaned there will be seepage of waste into cracks and crevices.
You have a defense of constructive eviction if the house is uninhabitable. Consult with an attorney first to review your lease and all of the facts.
This communication is not intended to create an attorney/client relationship. It is always recommended you consult an attorney in person to discuss your case. The Law Offices of Stage & Associates practices state-wide and represents homeowners and community associations. Please visit our website at www.stagelaw.com.
I agree with the other attorney about seeking legal counsel for at least a consultation. Based on what you have posted, it looks as though you properly notified the landlord of the issue pursuant to Florida Statute 83.51, and they at least stopped the leak. If you have not also notified the landlord IN WRITING of the issue, please do so about the cleaning still needed and mention that it relates to the sewage leak. The residual affect makes living in the property unsafe until a properly license cleaning/extraction company is hired. To do a proper job, you would normally need to temporarily vacate anyway and the landlord should abate the rent on a prorated bases for the time away to correct the issue.
In my opinion the proper thing for the landlord is to allow you to vacate early since you are close to the end of your lease and use the time to fully clean the property for the next tenant.