5 year old DS STILL has daily accidents, HELP!

[ChocFudgeCake]

Is it possible that there's something medical with him? Should I take him to see the GP? Or is it more a health visitor issue?
When I ask him why he did it he says he doesn't know or that he didn't realised. Maybe he is just attention-seeking... but at 5 years?? It happens during day-time. According to his teacher (reception), he is a happy boy.
Please help :(

Take him to the GP just in case there is an underlying bladder/kidney infection. If that is not it then I would contact the HV just to get some practical advice (if s/he is any good).

Thanks. Yes, I should send him every hour to the toilet. I forget and send him only when I can see that he needs to (when he has started doing little runs), but then it's too late. 2 years ago the HV advised to do that, I did it and after a while I left it.
I was thinking of getting him a watch that beeps every hour to remind him. I've got enough on my plate with a toddler and another on the way.