Yep, that 'doctor within' is THE most important one to listen to, for sure AND for certain.
Pain after flushing...hmmm, how many flushes have you done lately? how far apart? ANY organ (no matter how badly in need of flushing) can become stressed, sensitive, tender, and generall over-worked...especially when it's doing something that it's NEVER done before. Sometimes all that's needed is a break and a chance to rest a bit. Othertimes, of course, the pain can be caused from a new blockage that's been caused by unblocking something else. But generally speaking that kind of pain is intolerable, and can be lessened with a dose of ES...so if ES lessens or removes the pain, you have a good clue. If ES doesn't relieve or lessen the pain, you also have a good clue :)