The school was in Washington state and I was paid for being the mascot. I told them about it and had to stop working after I got a child’s skin infection from the suit.
A Washington attorney could advise best, but your post remains open for two weeks. Unfortunately, this looks like it would be a tough case. When you say "years," that raises concerns about statute of limitations issues. That aside, if other mascots did not suffer similar reactions to the costume, that could be problematic for your claim. They could be found and contacted; it probably isn't a very large pool of people. If that costume is no longer available for examination after all these years, that could also present problems. Your best option is to contact attorneys to see if they would offer a free initial consult to discuss the matter. Good luck
Tim Akpinar