If this site about rashes doesn't work check it again later, It seems like you may have porcelan fillings and i haven't really heard much about those but I have gotten some information. I could say your rash is from a lot of things but I am not a doctor. The best thing to do is to see a doctor, but I will give you this site that does talk about different types of rashes and you can take this to your doctor.
http:// www.familydoctor.org/545.xml
also this will tell you about your fillings www.mynewsmile.com/whitefillings.htm this site was written by dentist, I hope this helps.