My Son As Pain In His Stomach Since He Was

my son as pain in his stomach since he was five, we took him to the doctor and she did some test and told us that he has acid reflux, he has taken every thing under the sun and nothing works, now he has pain on the right side, he is 19 years old now and still as it, i have a family of colon cancer and i am worred, what can i do for him