You need to get your blood glucose
level both fasting and post prandial done.
If those reports are normal you could also need to get a prostrate examination, done from a surgeon.
UTI may also cause this trouble but with some other symptoms,it will be for less than a week
The stomach ache you are experiencing may be due to the urgency with which you need to pass urine.
Some times this also happens due to climatic changes or change in the ambient temperature of your room.