Usually a urine infection would come with a high temperature, infact in kids it is one of the things that will bring a high temperature consistently every 3/4 hours when the paracetamol wears off, and he might need to go more often or have pain, but the Dr will find this out, it still could be. Is he drinking a lot of milk or coke? or drinks with caffiene in? as this can relax the bladder and the sensation isn't as good, also constipation can affect bladder functioning. Encourage him to drink plenty of water or clear fluids. Hope he gets sorted, don't worry too much, it might help if you have a cotton with plastic coated underside dust mite cover on the mattress just in case, that way his bed won't be affected if he has an accident in the night & he won't realise theirs a plastic cover on.