How can I find a source of financial assistance for my Doctoral
Program at Phoenix University?

Borrow money from family or friends.

Have you asked Phoenix if they have payment plans ?

Usually, schools like University of Phoenix have exceptional financial aid counselors who are there to help the working adult find financial aid. I would imagine that they have counselors at your location. Ask the admissions office where to find the financial aid office.

Also, many doctoral programs have some sort of tuition benefit and a stipend for the student. The tuition benefit is given to the student in exchange for the student teaching a couple of lower level classes in the discipline. I would ask one of your advisors if these benefits are available for you.

I have options but you find the right information for that. You could apply for distance learning if that works better for you, you won't have to pay rent and you'll be able to keep a job, that would make everything easier for you. That's how I found <a href="http://creighton-online.com/programs/educational-leadership-degrees-doctorate-of-education.asp">doctorate degrees in education</a> and I am about to have my own doctorate in just few months. Good luck with your plans!