Get and ultrasound KUB with PVR (yes this is medical term), done, along with a urine culture. If both are okay, cut back on your coffee, tea and/or  smoking (if you smoke). You either have a urinary infection, stone or overactive bladder. Treatment of each ailment is different. Get your tests done and find put what it is??..that way you will achieve a long lasting permanent solution to your problem. Good luck buddy.