epsom salt troubles - can anyone help?

Last night I was going to do my first flush. I took one dose of the Epsom Salt at 6pm then decided that I would wait until the end of my fast to cleanse but the one dose of Epsom Salt kept me going back and forth to the bathroom until well after midnight. If I took 2 doses I don't think there's any way I could lay down for any period of time after the oil/juice. If I cut down the Epsom Salt dose will I still get the same dialation of the bile duct effect? Also, I felt really terraible after taking it, headache, nausea, sick feeling? is that common? I would really appreaciate any info or advice as I'd like to do the flush in just a few days to end my fast. Thank you
Lee