question: Whenever I eat crab I vomit and have diarrhea within an hour or two of ingesting.  I've had four incidents in the last two years.  It took a while for me to even think it may be crab as I'm lactose intolerant and kept wondering what dairy did I have to cause the reaction.I've seen an allergist and both skin and blood tests have come back negative for crab and other shellfish.  Even though the tests have come back negative should I be concerned about anaphallxis and carry an EpiPen?  Either way I'm not eating crab again.