thats definitely an infection, which is very common with mouth piercings
. the mouth is a very dirty place, tongue, lip
and cheek piercings
almost always get infected. the only way to prevent this is during the healing period, you have to obsessively clean your mouth, brush often, wash with sea salt water, and a good piercer will recommend using a special mouthwash. i forget the name, but its biotene or something like that.