Piercingggg

I got my belly button pierced about 4 years ago. I was told when I was younger I had a nickel allergy. When I got the piercing, the top hole kinda healed but the bottom hole never would. It was always kinda red and sore. I changed the bar to a plastic one and never had problems. I would like to have my nipples pierced. Any ideas on what I could use? The place that I called said they don't use plastic because of sterilization reasons which I completely understand. Any ideas?! TIA!