Hi.. Welcome to HEALTHCARE MAGIC.. I have gone through your query and can understand your concerns.. As per your complain hydroquinone as well as the chemical present in the teeth whitening agent both can cause chemical injury to the mucosa of different structures present in mouth and can lead to burning sensation when food is taken as there must be some amount of spices present in food which are further irritant and can irritate the already inflamed Oral mucosa.. In case if the burning is spontaneous and occurs without even during eating it can be due to a condition known as Burning Mouth Syndrome and can occur due to a number of reasons.. You should consult an Oral Physician and get evaluated and if it is due to burning or allergic STOMATITIS you can do cold water rinses and can suck on ice pops.. Gargles with a numbing solution during meals can relieve.. You can also gargle with steroids based Oral rinses for reducing Inflammation.. Avoid hot and spicy food and take a cool and bland diet.. Use alcohol free mouthwash.. On case if it is due to Burning Mouth Syndrome treatment of underlying cause can help.. Hope this information helps..