Yup - it must have been hemorrhoids from all the BM's. Its totally stopped as the afternoon wore on - I got a lot of watery BM's with stones in them! I can't believe this actually worked. I would say I got out about 100 or so green stones the size of lentils - some were as big as peas - and a few were white and did look like crystals all packed together - so all in all a successful first flush.
I feel much better now - although my left leg aches and, even though I've only had about two hours of sleep through this whole ordeal, its now 11:30pm and I don't think I'm going to be able to fall asleep tonight either. And yet, I feel pretty good. Weird.
Thanks for responding.
ps, I used to live in London, doing a student exchange program. Are you near London?