Can i ask any physician to run a mri instead of an x-ray because i've experiencing right pain in my groin and tightness in my left knee ?

Exam needed: No competent physician would order an MRI without thoroughly examining you first. Groin discomfort could be caused by strain of the inguinal ligament or a hernia. Occasionally it's from hip problems. Your knee symptom is very nonspecific. Consult a physician or orthopedic specialist and they will determine what testing, if any, is appropriate