Finding Plumbing Repair Assistance for Low Income Homeowner?

I live in Houston, Texas I am having major plumbing problems. I am constantly smelling raw sewage in my home. I am a lung cancer patient and also have my 3 grandsons (ages 3 months to 16 years) living on the property with me. I have checked everywhere I can think of trying to get help as I cannot afford to pay any of the quotes given to fix the problem. I am barely making ends meet as is. I am barely making it from paycheck to paycheck. Are there any charity groups or plumbing companies in the Houston area that can help?