How to treat or cure chronic aphthous ulcers?

Hi,

I get aphthous ulcers frequently. When one disappears after 2 weeks another forms. I brush and floss regularly and have used mouth wash, but the ulcers still occur. I did change my toothpaste to a brand that does not have SLS and it has helped a bit. The ulcers seem to leave a foul taste in my mouth. Are there any effective natural remedies? Or any dietary changes that needs to be aware of? Thanks in advance for your help.