For 5 days, mouth has irritation dark red dots. Mouth itchy for 15 min after eating (anything) discomfort persists afterwards;never had food allergies?

Need doctors exam. There is no way to be certain what is occurring to cause your symptoms. A virus or a reaction to food or medicine or another irritant or allergen could be to blame. You should have a history and exam by a physician. Ent is a reasonable choice. Try to take a duary of what helps and what makes it worse.
Doubtful. If you get symptoms after eating "anything" it probably is not due to allergies. Allergies are usually due to one or a few foods, not everything. More likely the symptoms are due to irritation or infection. I recommend being evaluated by you doctor.