Numb chin worry

I really don't know where to start. I was first diagnosed birthday breast cancer in 2012 and again in 2013, during chemo, with another different type od breast cancer, lobular. In the past year or so i have been struggling with hip/lower back pain. So much so i cant sleep laying down any more. Finally pushed to get an MRI down...just awaiting results but since then, more worryingly, I have developed a numb chin. Its been 3 weeks now and although bloods and head MRI came back fine, except borderline B12 deficiency, I am really worried that the head MRI is not a good enough scan for the nerves in the jaw as the area that is affected is the same as numb chin syndrome which is a red flag for mets...especially breast cancer mets. I understand that if this is in the early stages in the jaw area, an MRI may not pick it up. I also have the faulty RAD51D gene. Should I push for more tests...my doc first said she couldn't authorise a CT scan..and I don't have don't know if I even have an oncologist as I have moved since initial treatment. Anyone else experience a numb chin on one side?