What Causes Frequent Urination?

Question: Hi, I am 47yrs old male, Non-smoker, non-drinker, bad diet (low vegetables and fruits, mostly processed foods and coffee,some decent dinners like rice with beans and chicken mostly). Exercise=mostly walking non strenuous, My symptoms began last year summertime 2016. I have issues with constant urination and voiding two to three times a day which has increased in frequency this year Feb/March 2017. I had prostate exam done last year August/Sept. with no issues and Doctor prescribed Flomax which I finished in a week but still persistent issues occur, I go to the bathroom and take forever to completely void urination and then have to go again a minute or two later . I have been voiding(number 2) three time a day lately which has begun about a month ago.
Five years ago., I had pain in mid-section which I had sonogram test that showed inflamed liver. Had that issue for a month then went away (no further discomfort). Now, I need to be constantly near a bathroom which is causing great concern. I usually sit for many hours at a time using the computer(6-8hrs minimum). I am 5'10-weigh 200lbs. I also have Vitiligo Vulgaris. Hope it's nothing too serious that I can alleviate with diet and exercise. I have zero medical insurance.