Barium enema! help im scared! PLEASE!?

i have been severely constipated for 4 months my doctor even said he has never had anyone like this before! i am getting a barium enema what is it like compared to a fleet? i cant hold the fleet for more than 10 minutes what is it like holding the barium in is it tough or easy like nothing compared to holding a fleet enema and how much barium i used to get a litre enemas twice a day in hopsital for about 2 weeks (thats how constipated i am i had a football size piece of poop in my sotmach) please help me i am young and scared i am very worried plee help me!