Kudos on toughing out your flush. Sounds like it was rough, but a success - you got out stones.
I find that preparation makes a huge difference. I take malic acid caps and drink apple juice for the week before a flush.
I also follow each Epsom Salt dose with a big glass of apple juice. Cause I cannot take the taste of the ES, and it helps prevent me becoming dehydrated. I also drink lots of water up until it is time for the olive oil.