Very difficult and delicate problem. I can't improve on the advice already given, but I do think it's oversimplifying things to suggest that it's merely a question of finding an effective deodorant.
I've always found the claims made for deodorant or anti-perspirants to be exaggerated.* Obviously hygiene has a major part to play - particularly dental hygiene - but I think that you are either lucky or unlucky: some people have a strong body odour whatever they do.
I worked with a chap who may have had impeccable personal hygiene standards - and effective deodorant - for all I know, but whose clothes had always taken that bit too long to dry, and so he stank to high heaven of soggy undergrowth.
All of which is a roundabout way of saying: it's a battle that's fought on many fronts. Good luck
*[size=75]This may explain why I get a desk to myself in the far corner of the office
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