> Ate regularly all day. At night, had a big bowl of dry popcorn.
I am sorry to hear about your bad experience.
It is good that antispasmodic medicine works wonders for you.
Now, in your case, primary attack was most likely caused by corn intolerance (or fats that popcorn was made on).
Up to 15- 20% US population have some form of corn intolerance. (Not all of them recognize intolerance symptoms. Sometimes those symptoms are very mild.)
Very many people suffering from allergies, eczema, ADD-ADHD, celiac, psoriasis, digestive problems, IBD, IBS, constipation, .... have problems tolerating corn.
Intolerance is No1 cause of Gallstones attack. It doesn't always have to be a fatty meal. ( though popcorn always contains oils heated on up to 300C , and sometimes , it is even made on hydrogenated fats, oil )
But, attack can be caused by 100% fat free food, food you can't tolerate.