I have had a dull pain in my upper right abdomen and nausea after eating. Could this be a food allergy?

Unlikely. This sounds more like it is in the region of the gallbladder. If you eat fatty foods (or anything, for that matter) the gallbladder produces bile which might be squeezing against stones....Causing the pain and nausea. Have your primary doctor evaluate this, though a GI specialist might need to get involved.
Unlikely. That type of scenario maybe an indication of gallstones or gall bladder dysfunction. You need to see your physician.
Food allergies. Milk, eggs, wheat, soybeans, fish, crustacean shellfish, tree nuts ; peanuts cause 90 % of food allergic reactions. Up to 15 million americans suffer from food allergies ; need to avoid not only certain foods but any ingredient that contains proteins derived from them. In some cases, anaphylaxis can result. See http://www.Boston.Com/lifestyle/health/blog/nutrition/2013/11/the_dangers_of_dining_out.