My 5YO boy in the last few days have started needing a wee very frequently. For example, he needed as we walked to the park today. Twenty minutes later, we we were leaving the park, he needed to go again. This is unusual for him, he usually is alright to hold his wee in for quite a few hours. No pain, I asked. He has been toilet trained in the day time for eons! But still not dry at night despite several attempts (if relevant!). Should I worry or when should I worry? Thanks! 