Thanks for writing to health care magic.
Normally (majority) children achieve bladder control by the age of 5 years.
A minority take a bit more time to achieve bladder control.
Your child requires a detailed examination and further investigations to rule out the etiology of bed wetting
and the abnormal smell you are perceiving.
While you get the above done please ensure the following.
1. Do not let him take lot of fluids after evening hours.
2. Ensure that he empties his bladder before going to bed.
3. Do not insult or scold him for wetting bed...(easy said than done)
4. Try to identify and remove any stress
if present (may be at school or with parents or with friends)
5. Encourage him for not wetting the bed.
Hope this helps.