I find that the psychological aspects of needing to go can cause bladder spasms. Especially if I feel that I can't get to bathroom sat enough (I need assistance) then the urge is even worse! I found medications like Detrol and Uromax to be helpful.
Caffeine really irritates my bladder but I won't give it up.
...and yes, I have spells when the urgency and frequency is worse for a bit and then settles down.
Kathy, 49 with PPMS,full time scooter.
Married to a wonderful man, mother to a darling 9 yr old boy