Slightly embarrassing

Been with my boyfriend almost 4 years, he is the only person I've had sex with and its always been near impossible because of pain. It may be tmi but its a stretching pain when he inserts and an uncomfortable feeling throughout basically no pleasure unless otherwise stimulated. Been to the doctors and they believe its all in my head but its bringing our relationship down. I basically want to know if anyone else has slightly felt the same and what they have done to overcome it or help with it.