Urge for frequent urination. To urinate?

I am 29 yrs old(male). It's been few months I am getting the problem of frequent urination. Diagnosed two months ago. USG report was normal except the PVR was significant: 86.77cc (KUB ultrasound with PVR was done). Treatment worked that time (some medications). Now after two months I am having the same for last couple of days. As if something still remains each time after urinating. May be muscle is not relaxing fully. Also sometime I am getting slight pins and needle feeling and burning sensation in my bottom feet. Blood sugar was normal( test done 2 months back). I drink 3-4 litres water per day. Is it ok to urinate after every 1.5-2 hours(can't hold more than that) ,though sensation starts after an hour of urination, specially from post lunch to bed time period? Also I am feeling of having bowel gas, can it be the reason for the urge to urinate? No pain as such. Other activities are normal. Please suggest.