Lisa,

Body odor was one of the symptoms that led to my son being diagnosed with CAH at the age of 6.  It is a result of the excessive androgen production characteristic of this condition, so it could very well signal that your daughter is not well controlled, at this time. 

However, it still seems strange to me that a 5-month old would be exhibiting body odor, even if her levels were off.  I could be wrong about this---and someone please correct me, if I am---but, if that were the case, I believe her bone age (or hormonal age) would have to be about that of a pre-adolescent (the age at which one would normally get body odor), and I find that hard to believe of a 5-month old (especially one who has probably been diagnosed and treated since birth) no matter how poorly controlled.  If I were you, I would call your pediatric endo about this issue, just to rule out the possibility of anything other than undersuppression. 

Good luck!