Didn't it occur to you to use rubbing alcohol? I'm not sure if it'll work, but I think the petroleum jelly keeps the area too moist, which is why it isn't healing, and if by chance the piercing is in cartilage, it takes longer to heal. I have several ear piercings, which is why I’m telling you this, but my honest recommendation is that you see a doctor—they’ll tell you what the best option is; it might be taking antibiotics.