How would I know if I have developed an allergy to shellfish?

Many dogs few tricks. Many foods can trigger allergic reactions, even life-endangering anaphylaxis but those reactions have a limited number of symptoms - hives, lip, tongue & eyelid swelling, coughing, suffocation, nausea, abdominal pain, vomiting, diarrhea, a sense of something bad is happening, loss of consciousness & shock. If a some of these symptoms occur within 2 hours of eating shellfish allergy is possible.