Thanks Turiya. I have been away for a while and also did not get any email notifctaion that there had been replies, so just now finding this. Thanks for all the info - I will be busy now following your links.
I have indeed learned a great deal about stones - and haven't had one since 2009.
Not sure what inspired the comment "hooked on heroin" - taking one single dose of pain medication when in extreme pain hardly defines hooked. This is the exact situation that such meds are for.
Again, thanks so much for taking the time to provide the detailed info!