I forgot to tell you one thing:
It sometimes takes a single flush to get the stone out ... especialy for men.
I would have taken that chance, before considering any surgery or any other medical procedure!
Also, many people who encountered severe pain when spontaneously passing Gallstones (what actually happened in your case), they have had no pain at all when passing far larger stones while doing a flush. Epsom Salt and olive oil can do miracles!