Ron
I am wondering whether I struck a similar problem as to what you've described. I just did my first flush couple of weekends ago and suffered pain I thought had long gone and was pretty bad in the centre of my chest. After taking Buscopan it relaxed considerably (it helps stomach spasms etc).
Anyway to answer your other question picture this. Acid in stomach mixes with
OO (Olive-Oil) flush ingredients it reacts and further breakdown commences, being largely fluid already it is then expelled into the Duodenum along with current acid contents of stomach. The duodenum now contains the acidy/flush material. The receptors in the duodenum walls signal the liver and system that bile is required in MAJOR quantities (how major I don't know but lets say this is lots). This is due to 1. Acid and 2. Fats (the OO). Bile being alkaline has to help breakdown of fats and neutralize the acids. In this case lots of bile is pumped into Duodenum and due to volume overspills into a stomach which is low right now in acids. Too much alkaline in stomach - therefore -potential irritation. Meanwhile the Gallbladder is spasming its little heart out trying to fulfil the need for bile along with the liver. At least this is the theory of the gallbladder workings and flushing. The Duodenum then starts to release the mixture into the small intestine and the stomach acid levels increase, but meanwhile your stomach was upset with the alkaline it never experienced before and 2 your gallbladder is still spasming from overwork it never did before.
I wonder sometimes whether our diet should have MORE fats to make these organs work more frequently I am actually a low fat consumer with below average cholesterol readings yet still have a gallbladder problem.
cheers..