I have similar symptoms. Twitches or spasms with urinary tract pain.
We've just about narrowed it down to the bladder in my case.
My current uro is thinking it's probably cyctitis or some other type
of infection.
I'm certain it's bacterial as I respond to ABX's.
The spasms and uti pain diminish almost completely though I still get
some pain in the bladder(stinging)and occasional burning during
urination.
They haven't found anything in my urine to indicate an infection but
are letting me stay on the antibiotics to relieve symptoms.
Have your uro do a ultrasound of your bladder to see if your voiding
completely. That's what convinced mine that it wasn't the prostate.
(I have a normal PSA and no enlargement of the prostate, just some
calcification.)
Don't be too disheartened, your not the only one to get these problems
at your age. Mine started at 38, others have had problems as young as
19.
You cantry the broccoli treatment to ease any discomfort when
urinating.
Just boil some broccoli in water for a few minutes then drain off the
juice and let it cool. drink this a couple of times a day.
You'll see relief pretty quick.
I do this when I have extreme bouts and it helps to improve urinary
flow, relieve burning in both bladder and urinary tract.
you can also eat the cooked broccoli to help with bowel movements.
Constipation and bowel disorders play a major role in prostate/bladder
ailments.
Use either fresh or frozen, both work equally well.
always boil it, this is what releases the effective elements in the
broccoli. Uncooked broccoli is to difficult to digest and most of the
intracellular material that acts to cleanse the bladder/prostate pass
through undigested.

Sounds like prostatitis to me. Did your Uro press on your prostate? Did you
feel pain??