S.M.
Hi L.,
My son used a pacifier and the moisture from drooling when he was teething got trapped behind it and caused a rash all around his mouth. I had to keep the area around his mouth as dry as I could. I also had to find a pacifier that was vented, not one solid piece. It worked for us, hope it does for you.
Something to soothe his gums - I took baby food bananas by baby spoonfuls and put them on wax paper in the freezer. After they harden, give them to the baby. Soothing and nutritious at the same time. Just make sure they aren't large enough for him to choke on.