Every time my son wears his sports mouth guard his mouth becomes very painful, burns, white spots on them to the point that he cannot sleep at night, talk or eat. This is his 1st time playing lacrosse and it requires a mouth guard. I have gone through 5 different ones. Most of them are made of silicone. Has anyone heard of this before and is there a solution? Are there mouthguards made of something other than silicone?