Hi Karl, I get the same issue, I am 3 yrs post surgery. The only difference is that the excruciating pain goes away immediately after urinating. This bladder spasm (nocturnal) I feel also contributed to my night time incontinence, I have observed sometimes when not in feel sleep, I would wet myself subconsciously to relieve the pressure. This is the reason for my night time incontinence. Like you it only happens when I am lying in bed sleeping. I have taken several steps to reduce the urge to urinate at night, the one that seems to work is no food or liquid intake after 6pm and no rice or carbs after 4pm. Funny enough last night, I accidentally slept without pads, I got up once to urinate, I was also dry in the morning.
Good luck with finding a solution or answers. My biggest annoyance is the bedwetting, as it has affected my qualify of life with respect to travelling with the lads, with the shame of waking up and flooding the bed.