My daughter started having b.o. at 5, she was diagnosed with precocious puberty at 6. She had other signs though aside from this that led me to believe she was undergoing puberty early: breast buds at 6, she was (and still is) very tall and off the charts in height and weight when compared to girls her age, mood swings and an enlarged uterus (seen in her pelvic MRI). It could be that your daughter may just be sweating a lot due to the weather. Using an anti-bacterial soap instead of baby soap will also help.
My daughter doesn't have breast buds I don't think but is also incredibly tall (wears 10-11 clothes, off chart etc) and I'm only 5'2"! She also has mood swings which I mentioned to the GP when we went. I keep wondering whether to go back as she will often cry and say she doesn't know why etc. The GP did feel her tummy though and say she didn't think there was any cause for concern but I'm not convinced.
Amy, they did a bone scan of my daughter's hand and they found out she was 2 years and 3 months ahead in bone age and showed advanced skeletal maturation. We were consulting with her pediatrician from birth at first, but he just said that it was nothing to worry about. My friend then recommended I see a pedia endocrinologist and that's when she was diagnosed with PP. She is 7 and wears size 12 to 14 clothes. She is 4'7" and 90 lbs, the tallest in her 2nd grade batch. If you are still having doubts, maybe you can schedule an appointment with a pedia endocrinologist.