I'm not Shelley, but I have been doing the Hulda Clark and Andreas Moritz flushes for a long time now. You need to drink plenty of water on the day you flush. Gradually taper the amount down as the day goes on. I actually keep drinking some water or apple juice right up to the second dose of Epsom Salt with no problem. However, I am very careful not to eat anything solid for at least six hours before taking the oil. My stomach needs to be empty when the oil hits it. Another thing I discovered on my last flush is using the product EmergenC. I used it several times throughout the day of the flush; I took my last dose immediately after drinking the second Epsom Salt drink. The next day I also used several packets of EmergenC. This really helped with getting rehydrated. I also ate lots of Watermelon after flushing. This helps rehydrate, contains lots of minerals for electrolyte replacement, is good for the kidneys, and it tastes so good.
Dehydration is not a serious problem during flushing as long as plenty of fluids are taken. Don't just chug large amounts of water all at once. Keep sipping water all day long so your body will have time to absorb it. Drinking fruit juice will supply extra minerals. Apple juice has potassium as well as the malic acid that helps soften stones, plus pectin to help the bowel. If you want to avoid the Sugar in apple juice, you can either make a raw apple cider vinegar drink or dilute the juice.
I no longer flush every two weeks because I have finally got most of the stones out. However I continue to flush every 4-6 weeks because I have to take pain medication and that seems to trigger the formation of stones in me. In fact my doctor thinks that one reason I had so many stones (over 6000 from BB sized to the size of a marble)was because of using so much pain meds. I took Tylenol#3 for years as prescribed for migraines. That product will never again passs through my lips, but I still take Ibuprophen and prescription Ultram and they also seem to trigger stones. Just saying this to point out that Liver Flushing is great, but lifestyle changes have to be implemented as well for optimum health. Good luck.