Underarm smells since becoming pregnant.

Anyone having the same issue? Any idea whether it had anything to do with "fish oil" supplements? I do not have this issue with my 4 other pregnancies. It smells like wet used mat/towel, not properly aired. Ps: that's the only way I could describe as I noticed the same kind of smell on my son's towel when not properly hang/aired or the toilet mat when my hubby wet it while rinsing the floor and left overnight. Underarm only smells great for a short while after showering. Then the bad smell will appear even without sweating. So annoying!!!