Babies allergic pacefier?

ok so my baby is 7 months old and when she was 5 months old she started to get this red spot on her chin so I asked the doctor what was that red spot and he told me that it was because her pacifier so I took her pacefier away it wasent easy but I had to do it and the spot got worst and it started to spread it doesn't bleed or anything its just bright red I tryed to put petroleum jelly for bbs but it doesn't go away I just want to ask if babies could be alergic to her own saliva? Or what to do so it could go away?