crohns disease age 14

Hi my name is noah. I am 14 years old and was diagnosed with crohns disease when i was 11. The last three years have been very difficult. At first i was put on prednisone for a year and after being weened off of that i was put on pentasa and other crazy meds. I was taking 8 pills in the morning and 6 at night. I was still getting sick and am continuing to be sick 3 years later. I have missed more school than i have went and it is just very stressful being a freshman in high school along with having this disease. I couldn't take the pain any longer. This past summer i had read into medical marijuana. I had had smoked once ever other day and started feeling great. I though i has an answer to how i was going to deal with the pain. After a month of smoking and no pain i was caught on a drug test. I am now tested monthly therefor i cant smoke. I have pain again and am having a hard time dealing with it. I have no idea how to pursaude my parents that weed isnt as bad as everyone thinks it is. I need help.