DJB,
While only your doctor is in a position to determine a cause and offer solutions, What you describe is not unusual.
ALWAYS check with your doctor before listening to me or anyone else.
We can commiserate, because your husbands story is known to many - we hurt and answers are way to slow in coming.
Initial symptoms that sent me - and countless others - to the urologist included:
Inability to urinate despite a feeling of great urgency,
Voiding tiny amounts 10 to 50 ml at a time.
Feeling a need for a bathroom every 5 or 10 minutes
Burning with and without voiding,
Bladder pain and spasms.
Pink to bright red blood and clots.
While being treated by the doctor, these same symptoms reappear for a while, as the bladder had been intentionally irritated with BCG - the amount of irritation does seem to vary from individual to individual. I have had to have a catheter, and made the midnight run to the ER to be cathedwhen I could not void at all. Again, not uncommon, as I have been assured by my doctors.
What helps ?
Simple things I have found include placing a hot water bottle (microwaved wet towel) on the bladder to relax spasm.
Urinating (with or without catheter) has been easier in unusual posture when problem arise - an attempt to relax the bladder muscles - for me, standing, leaning my torso over the bathroom sink while holding a urinal or when catheterized, made voiding easier. Standing in a warm shower, water over the lower abdomen, offered relief.
LOTS of liquid in, even when little is coming out, eventually helps for me, and has been recommended.
If the doctor allows it, AZO or pyridium tablets - over the counter urinary relief pills, not heavy pain meds, this has helped me.
Hopefully, the doctor will have helpful suggestions to increase comfort.
Best
Jack