What causes canker sores & sore throat? I have canker sores on my gums, under tongue & sore throat after eating spicy pork rinds, cherries, garlic nuts.

Unknown. Canker sores or apthous ulcers are most often attributed to an autoimmune reaction of the mucosa. The causative agents can vary among persons and there is no known cure. The best thing you can do is take note of the foods/drinks that cause this for you and avoid them if you can. If you get them bad enough a topical steroid intra-oral med can be applied to them to minimize the outbreak.
Avoid those foods. Your complaint is very common and the simple answer is to avoid those foods! canker sores occur as a reaction to some types of allergens, such as citrus fruits, walnuts, chocolate, and many others i could mention! i don't usually mention products but patients who use rembrandt canker sore toothpaste don't get canker sores anymore!