Are family docs allowed to order mri? can i ask one for my pelvic injury and pain?

Yes ; yes: Your family doc can order just about anything s/he wants. Whether s/he will do so depends upon whether s/he feels it's appropriate ; necessary for you. Then there's the question of whether your insurance will pay for it (or not). Best to chat w/your family doc ; undergo thorough evaluation as to nature of injury ; description of pain especially what makes it better/worse.