I have horrible allergies
I have allergies that are mostly seasonal but really bad allergies to corn pollen which is unavoidable since I live in Iowa. 
I have terrible allergies too- especially to cats. What other kinds of allergies are there?
Food allergies and allergies to all types of pollen. That's why during certain seasons people develop hay fever especially during harvest.
What exactly causes allergies? 
It's a hypersensitivity of the immune system that is triggered by things in the environment. 
How are seasonal allergies different from food allergies?
Allergy
Allergies, also known as allergic diseases, are a number of conditions caused by hypersensitivity of the immune system to typically harmless substances in the environment. These diseases include hay fever, food allergies, atopic dermatitis, allergic asthma, and anaphylaxis. Symptoms may include red eyes, an itchy rash, sneezing, a runny nose, shortness of breath, or swelling. Food intolerances and food poisoning are separate conditions.
Common allergens include pollen and certain food. Metals and other substances may also cause problems. Food,
seasonal allergies called “Extreme allergies and Global Warming”, have found that many allergy triggers are worsening due to climate change. 16 states in the United States were named as “Allergen Hotspots” for large increases in allergenic tree pollen if global warming pollution keeps increasing. Therefore, researchers on this report claimed that global warming is bad news for millions of asthmatics in the United States whose asthma attacks are triggered by seasonal allergies. Indeed, seasonal allergies are one of the main triggers for asthma, along with colds or flu,