You have described a little white bump that appears on your tongue after eating salty or sweet foods. This is actually not a typical appearance of a canker sore, which usually appears on the inside of the cheek or the roof of the mouth. It commonly appears as a whitish-yellow wound with a clear red border. In addition, a canker sore can be very painful, which is a symptom that you have not mentioned. One possibility is that you are in the early stages of canker sores, which begin with a tingling, uncomfortable feeling, with a small bump showing after a few days. This then leads to the final stage, which is an open sore. However, it is advisable that you visit a doctor to get a proper diagnosis, since there are several conditions that could cause a white bump or spot to appear. In addition, conditions such as iron deficiency anemia, vitamin B12 or folic acid deficiency, and gluten intolerance also form similar ulcers inside the mouth.
If your doctor does confirm a case of canker sores, the most likely cause in your case is a food allergy. Avoid salty and sweet foods for some time; it would help if you knew which exact foods first caused the white bump on your tongue. In almost all cases, canker sores typically heal themselves after a few days, and you can be treated at home. In addition, try some home therapies that can bring relief from any discomfort and speed up the healing process.
Avoid eating foods that are hard or crunchy, since these will irritate the open sores. Also stay away from acidic foods such as oranges, lemons, and vinegar. Soak a cotton swab with a solution of equal parts water and hydrogen peroxide and apply directly on the sores, gently. Similarly, apply milk of magnesia which is very cooling and soothing. You can also rinse with an antiseptic mouthwash several times a day. A natural alternative is a solution of aloe vera, which has excellent antimicrobial effects and can help to heal the affected skin. Your local drugstore should have patches containing liquorice root extract; apply these directly over the sores to heal them. If you smoke or consume alcohol, quit immediately since these are known to irritate the open sores and slow down healing. In your diet, try to have mild, non-spicy foods that do not require much chewing. Follow these tips for few days and your sores should go away