Which flush to do/how?

Hi,
I'm new to the forum. Last year beginning around May I suffered from severe stomach problems which was finally treated (acid reflux and chronic heartburn). As a result of the stomach problems I lost about 30 pounds in 6 months and thought that the pain I had under my right ribcage adn right side of my back was due to tension and stress left over from the stomach problems. In a way it was, anytime I had fried fatty food it would flare up. After going into the doctor for the second time, a different one, she said it was classic gallbladder/stones symptoms (something that I already suspected.)I've adjusted my diet although it's still a little bit trial and error and the pain pills I was prescribed until then (tylenol with codeine) only cramps me up, abdominally and in the area of my gall bladder. I go in for a ultrasound on the Monday the 21st but would like to do a fast and flush before then. My question is basically would that be okay? Which one should I do? I'd like to do ideally a 3 day fast and then a flush this weekend? Suggestions? In the meantime, I'm continuing to enjoy and learn based on the information on this forum.
Thanks,
adrian