My Husband Is 46, Is Having Pain In The Right

My husband is 46, is having pain in the right side of his neck with numbness to his cheek and jaw, after what seems like is a hot flash, hot and red all over. It is creating difficulty swallowing. this happened yesterday also, and he went to the ER where they did tests and said everything was fine. This is new for us... any thoughts? He did just eat pizza.... could this be an allergic reaction to gluten