I have a child who suffers terribly from bad body odour. It started when she was 6 years old. I had to bath her first thing in the morning and she would start to seriously smell of sweat by noon!
She has a very sensitive skin - I couldn't just try ordinary underarm products. I didn't want to use pills for a 6 year old. After surfing the net for weeks, I came apon a very simple solution and thought I couldn't be this easy, but it worked. VICHY Laboratories has an underarm deodorant (roll on) which functions totally different from other products. It actually solves skin problems. The have one for sensitive skin which lasts 24 hours and one which lasts for 48 hours. It really works! My daughter applies the roll on after her bath or shower in the evening and voila! Its 3 years later now and she can even goes on school camps. I have told our GP about this, and she has told many moms about this. I also know many men who have switched to VICHY.
Lastly, if you suffer from bad breath, but keeping your mouth extremely clean doesn't solve the problem, drink probiotics (in powder form in a capsule) everyday. Give it a week and gone is the bad breath. You must continue to drink the probiotics for the rest of your life - it is good for you!