I would def go and see about it. A continence nurse or someone specifically trained in that area will be able to organise a plan with you and your son. There are a few types of incontinence and sounds abit like urge incontinece, usually your bladder gets filled to a certain point and sends signal to your brain that you need to go then your brain sends signal to the bladder to hold on til an approriate time. Somewhere that signal is getting lost, your son gets the message he needs to go and he goes.
The continence person plus the DR will work on what the cause is behind this and work on what can be done to help.