I've had my ears pierced for a good 3 years now, and about 4 months ago, I put in a pair of earrings that caused my piercings to become infected. I took them out, treated the infection and everything has been fine. I haven't put any earrings in since then, however today, my left ear, which was the worst the first time around, is suddenly infected again. Earlier today it was fine and now tonight it was burning and swollen and I had to 'pop' it so to say and get all the pus out which had a yellow tint to it. Why is this happening and what can I do to prevent it again?