Urethra discomfort after urination and frequent urination?

Have had a yeast infection since Dec.2011 which keeps coming back (treated with Diflucan)as of 04-07-2011 neg for yeast,bacteria, chlamydia, and the symptoms in my question all started around the same time in Dec. The urethral discomfort only happens a few minutes after I urinate,not while urinating.Also have been experiencing more frequent urination. Doc says the the urethra symptoms don't relate to a yeast infection.Doc examined and tested me for every kind of infection,and every kind of STD..all negative. He showed me I had a yellowish discharge,no odor, tested me for cevicitis also. So far nothing. I never have had any problems before and have been searching the net and not found anything conclusive,a lot of the vaginal problems sound a lot alike so it's very frustrating. Sex with my hubby of 14 yrs, once or twice has been kind of uncomfortable. I would appreciate any kind of help, or questions to ask my doc. If anyone has ANY of the same problems or information it would be GREATLY appreciated. :)