I Have Tried To Prep For A Colonoscopy 3 Times

I have tried to prep for a colonoscopy 3 times & today now is my 4th it makes me so sick even with the new preps.
can i have an mri instead?
my cat scan showed moderate obstipation & i have been using miralax
i do have pain on my left side & bloating & weight gain of 6 pounds over the past months
the cat scan nothing else but a gall stone which i knew i had and no problems