new problem with underarm odor

I'm hoping someone can assist me with a pretty recent issue that I am experiencing. I have never experienced underm odor, even if I forgot to put on deoderant. However, about 6 mos. ago I began experiencing underarm odor, despite not sweating. I changed my soap, and switched my deoderant twice. I even use peroxide at times. While it has lessened somewhat, there is still a slight odor. I don't know why this is happening. I don't know if this is due to a thyroid problem, or something else, but I can't figure it out. Does anyone have any ideas? Thanks