You could try camomile tea - it's anti-spasmodic and sedative. I drink it when I'm feeling emotionally wobbly or wound up and also when my bladder plays up. It's one of the safest herbal teas out there, but if you haven't tried it before, maybe just one cup and see how you go as not everyone can take it.
I usually drink one cup a day (at night) and if I get bladder issues, drink 3 cups one after the other, which usually sorts it out (it's not good to drink large quantities continually as it can actually cause irritation then instead of easing it, but as a one off to deal with a known problem, it's fine)