What are three possible problems that could have caused farley's symptoms?

Anaphylaxis, serum sickness and toxicity from food are the three problems.

Anaphylaxis refers to a severe and very serious allergic reaction which should be treated right away otherwise it may caus death, Serum sickness is also similar to the allergy and in type II hypersensitivity and clinically we can say that the reaction due to the medicine that does not contain protein. Toxicity from food refers to the food poisoning that is caused by contaminated food.