I Have Parkinson's Disease, And This Has Increased My Need

I have Parkinson's Disease, and this has increased my need to urinate, but accompanied with cramping that makes it somewhat painful. My urologist tells me that he can't do anything for it, as increased dosage of something like Alfuzosin will lower my blood pressure too much. Would taking Zyrtec for allergies of being exposed to pollens worsen my urinary problem?