Last MRI

My cancer is agressive, my doctor suggested one more MRI after my two lumpectomies but I had not received clearance from insurance company for coverage. My doctor had marked my request stat...we'd expected a possible confirmation on the same afternoon but with the holiday coming up it seems no one was available to review my case.
My doctor suggested I go to the Radiology center anyway. He said they would run the test even without the ok if I were willing to sign a paper. The paper I signed says I understand that if my insurance company won't retroactively cover me I will take responsbility for the last MRI.
Ok. I signed it. They did one more MRI. The results show benign and I have begun my daily radiation therapy, but not I'm super worried about that bill. My ability to work has decreased since my Cancer diagnosis. It's not that I get tired more easily, it's that I get marginalized at work. I worry as a self-employed person that perhaps people are less likely to employ me since I have a radiation schedule.
Please help me pay for this last MRI. Allow me to focus on keeping my immunities up and making my radiation appointments.