You seem to be having urticaria or skin allergy. Sometimes it takes very long time to stop. Please visit your dermatologist and take regular treatment.
Next Steps
If you have any dental infection like tooth decay or any tooth which needs root canal treatment please sort that first. Hidden infections in body can cause skin allergy.
Health Tips
As far as possible try to eat food cooked at home. Try to avoid eating food outside, esp those with artificial color or excessively oily food.