I'm starting to really stress out now :( Gonna cause myself to have an anxiety attack I know it

I've never noticed it before, but I never look at my armpit in general really. It's dark ish, but it's not enlarged or anything. Feels flat, but my skin is kinda covering it too, so the only thing I can feel there is my skin. Like it looks like two different spots cause my skin is over it in the middle, but it's not big either

I have a skin tag on my other arm, but I don't think it's that.

I know when I went because of my tag my doctor said I should look out for moles that change size and colour.

I'm a guy 33. Not sure what to do