Odour yet no wetness

I'd be grateful for your thoughts. I started using a 'problem' antiperspirant called Triple Dry six years ago because a medication was making me sweat more. It worked perfectly - no wetness, no odour. I've stopped taking the medication now, but have carried on using Triple Dry because it works so well. However recently, I have noticed an underarm odour, despite the fact that I have no wetness. The odour isn't there all the time - it mainly occurs during situations where a person might typically sweat e.g. when doing exercise, sitting in the sun. I'm confused because I thought it was 'wet sweat' reacting with bacteria that causes odour - yet I don't seem to have any 'wet sweat' (at worst, the skin is very very very slightly clammy at times, but mostly it is completely dry). I've even tried putting a layer of Rexona on top, but still have the odour. Do you have any idea what the cause might be? Or a solution? Many thanks.