I can understand what you mean that its extreme painful, I been there.
If I was in your situation I would flush and continue until I feel better and I'm completely clean of stones. I'm on that journey, I have done 20 flushes so far and trust me it gets better.
I have not read that book by Moritz, but I have read the The Amazing Liver and Gallbladder Flush, edition 2012 and does mention about trying to eliminate being on medication before doing a flush. Again if I was in your situation, I would do the flush because whatever is stuck or causing your pain, needs to come out. Flushes will only get you better, sometimes we need to get worse before we get better because we need to get all that stuff out of our systems. When we do cleanses like the flushes, you will have discomfort, pain and sometimes you will have to repeat the flush within a couple of days or even the next if you feel like you need to. You have to listen to your body, everyone is different and only you know what feels right for you.
I would recommend doing the preparation of the 5 days before the flush using pure tart cherry juice, it has 4x the amount of malix acid then apples do. I started using that in my last 2 flushes and I like better then the apple juice. I learned that in reading Moritz's book on the flush.
Another thing I would recommend for you based on my experience: 1.avoid eating after 6pm
2. try to avoid any fats that are not natural, consume: avocado, olive oil, nuts, but if you see that you have pain or that nuts for example cause you issue, don't eat it
3.eat your heavy meal around noon
4. try to stay on a plant-based diet
5. drink lots of beet juice
6.lemon in warm water in the morning
7. take herbs to help dissolve/soften the stones:
chanca piedra, GCG,hydrangea pills
8. herbs to help detox the liver: Chinese bitters, dandelion greens, milk thistle, beets, anything bitter is good for the liver.
9. drink lots of water
10. peppermint or turmeric tea, amazing when you have pain or discomfort.
I highly recommend the book I mention above by Moritz, very helpful for anyone interested in doing the flushes.
I really hope this helps because I understand your pain. Also read all you can all about people experiences with Liver Flushes here on curezone, I have learned so much by just reading others experiences.
Let me know if you have any questions, more then happy to share my experience and what I know about doing the flushes.