Yep, Anonymon...
your descriptions made me grin...they were spot on!
My spasms also have lasted up to 12 hours.
Whimper, flat out cry, accidentally hold me breath (what I do instead of screaming).
Today is 2 weeks on nifedipine/lidocaine. My CRS says he's seen huge, buff guys, weightlifters and football players sit in his office and cry like babies becuse of the pain.
No, you are not a baby. I know the looks though...get brave enough to tell someone and they think you are crazy.
Spasm is not a good word to describe it. Other folks must be imagining it to be like an eyelid twitch.
The worst is the sleepless nights of agony. But, I don't have the "pooping glass" pains that others have during BM.

I think the peristalsis of the intestines may affect the length and severity of the spasms, which is heavily influenced by when you eat. In my case, I eat early in the day within a 5-6 hour period, then pretty much fast the rest of the time. As the day progresses, everything about the spasms goes down. Sometimes before bed, it aches and burns, but I think in my case that's my intestines moving from all the Milk of Magnesia. I also poop first thing in the morning and then again after, but the spasms lessen in the later ones unless I had a retear, despite the poops being identical.
So if anyone's spasms are giving them sleepless nights, you might experiment with getting done with your eating a bit earlier.

Actually, for me...I think that around 9:30 to 10 pm *I* finally relax...so my butt says, "Hey, now it's my turn!"
Fortunately, it's down to once a week now, instead of three nights a week trying to sleep in a hot bathtub.