Help with my 7 month old!!?

Ok my son is 7 months old, 2 days ago I noticed a small pimple lookin on his top lip, I didn't think ne thing of it because these are normal for him he drools a lot and loves his pacifier which holds the drool on his lip and sometimes makes these spots. However, yesterday this small spot turned into a swollen and red spot which came to a head and today it is still very swollen and red and still hasnt popped. Ne ideas besides the doctor which I am waiting on to open.