Stinging tongue/lips and feeling nauseous. is this a food allergy?

Yes: Most likely a problem with oral allergy syndrome which is a cross reactivity issue with certain raw fruits and vegetables which have similar protein structures to some pollens like ragweed, birch tree, grass or mugwort.

Maybe: Nausea indicates lower brain stimulation. The easiest way to treat yourself is to get rid of the "junk" in your diet, particularly sugar in all its forms.

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.