Diagnostic numbing shots for teeth.

Have been dealing with lower jaw pain under ear and side of neck for more than 10 months. No injuries. It's like burning and sore pain in the jaw under ear and neck. Been to multiple doctors and dentists. They said it's Myofascial pain dysfunction. I do have muscle tightness and stiffness.  I have 2 lump like spots in jaw under ear and neck. The lump in neck is pea like size and hard. It's the same from June'20 till now. No change in size. My physician ordered neck ultrasound,CT scan.Normal. Whether it's pinched nerve? Extracted upper wisdom tooth and rct on lower molar 46( suspecting tooth root fracture,cbct clear,no cavity. 46 hurts for tapping and biting pressure before and after RCT )Pain is constant under ear & neck. 46 hurts for tapping,biting pressure. dentist want to try numbing shots to see if cause of my pain is from that tooth or not. is it safe? how to find find fracture with numb shots. Will numbing shots safe to try to isolate cause of my pain? Will it help?