Of course that amount of caffeine is going to block pain temporarily.
I like Andreas' advice about knowing when to quit. If you get two consecutive flushes, following the entire protocol for preparation (malate, etc), and using epsoms, and you get two consecutive flushes with no stones, you seem good to go.
Otherwise, without following the preparation, etc. you could indeed get lousy results and false positives.
Also, there is no such thing as a parasite free liver in my opinion. If you expect to advance I think you should consider (my opinion of the best way to go) a combination of Miracle-Mineral-Supplement and Hulda Clark 's protocol. You will, assuming you have the eye for it, rid yourself of beaucoup parasites. Many of them will be making it impossible for stones to release. If you do a Liver Flush at the same time as peaking on the Miracle-Mineral-Supplement and Clark protocols you will be astounded. It's ASTOUNDING unless you are a rare person that avoided this horrific mess we've gotten into on this planet with filthy food and water and all the parasites they cause.
Both protocols are cheap though. That's the good news. Miracle-Mineral-Supplement is not that easy to take though. You will get nausea and diarrhea when the kill shots are delivered. In my case I though my guts were coming out. Nope, not guts .. just thousands of parasites of ever imaginable size, shape and color. And I've been a vegan for many years, even half raw. Forget raw or vegan for killing anything. That is not their mission.