What "gall bladder herbs" are you taking? Have you done any liver flushing? Are you on a low fat diet?
The fact that you released gall stones after eating a big quantity of ice cream (assuming it has fat it in as do all but non fat ice creams) suggests that your gall bladder was working well enough to expell stones in response to a high fat food.
I don't know what a "gall bladder attack" is, but to me it seems wonderful that you have expelled stones.
When I do Liver Flushing I always include a big serving of high fat ice cream on the night of the flush, and my gall bladder also responds by being active.
If you have Gallstones and liver congestion, a Liver Flush would be great for you as the Epsom Salts relax the gall bladder and liver ducts so that waste material including stones can pass out of the gall bladder and liver without pain.