There are many things that can cause frequent urination and a urologist is the one to help you rule out what is causing your symptoms etc. You could just have an over active bladder and they have several medications for that.
It also could be chronic cystitis or interstitial cystitis. With these you usually have pelvic pain too. The self help things etc. can help you while you see a diagnosis!
We have an Bladder support forum here on this site actually two, There is actually an article on the physical relationship on the first forum. I am also an IC support group leader and director of MOARK IC. If you need more info or some links feel free to pm me.
You might want to consider a referral to a pelvic pain PT. They are often able to rule out and pelvic issues, muscular etc. that doctor's are not trained to look for.
http://www.medhelp.org/forums/Interstitial-Cystitis-IC--Pelvic-Pain-Support-Forum/show/412
The expert forum where you can actually ask the doctor here on Medhelp is here also:
http://www.medhelp.org/forums/Interstitial-Cystitis-/show/264
Hope this helps!
Shelly