ive seen these problems online often and i once had something similar; what worked for me was changing the band. your skin could possibly be allergic to the material used in certain bands. if you think that could be a valid reason, then find a band that's allergy free. it could also be that you wear your watch too tight, this was the reason my skin was irritated. i switched to a magnetic band that allowed me to precisely place the end of the band wherever i wanted, allowing for more comfort compared to the standard holes in the band. wearing it loosely helped for more comfort and less skin irritation.
hope this helps!