I am 57 and I have the same problem since my childhood. I consulted lot of doctors and got various tests conducted that includes blood tests,urine test, x-rays (IVP etc) but nothing has been reported and the doctors said nothing in there. Lately one hospital identified that the flow of unine is very week and that is the indication of prostrate enlargement. Naturally, prostrates do not develop at age of 5-6. In my case, in cold weather, frequency further increases.