Mast cell diseases, like Mastocytosis, occur when the body has an excessive amount of mast cells. Due to the amount of mast cells in a person with Mastocytosis' body, they can get very sick and experience symptoms such as skin rashes, nausea, vomiting, headaches, bone pain and skeletal lesions, and anaphylaxis. The mast cells can be triggered by heat, cold, perfumes, medicines, and insect bites.