Throbbing pain above left ear on one sid

Mom started having headache on left side of brain above ear going above due to some stress in family den she started having very unbearable pain for a week and she was unable to bear it they went to a neurologist who gave her few medicines and asked to complete the course for 10 days and if the pain does not stop den get an mri done. After the course my mother did not havethat throbbing pain but she is having slight pain and she again got it for continuous 4 days which was bearable. Why is this happening? Can this be serious doctor has told her that if the pain is not much den no need to go for mri due to harsh radiations kindly tell what can it he due to? Whenever she stresses about anything she gets this pain? Is there anyproblem in nerve or any clotting. What should be done