Thanks for your question and concern about your issue. Mostly, sores like you said, which occurs in tongue is likely to be canker sores or medically called aphthous Stomatitis.  They are painful little sores or blisters which become more painful while eating acidic foods and citrus fruits. Also, they can occur more than 5 times a year and mostly once in every 2 months or more or less frequently. The real cause of canker sores is unknown but they are harmless in a way. They are not caused by any deficiency or nutritional disorders. Some research studies state that normally those sores are due to lack of folic acid or vitamin B12. Lack of iron also adds to the worsening of canker sores. But even researchers are not able to confirm whether these findings are true or not. In general evaluation, a doctor can find whether  it is canker sore or some nutritional disorder. Moreover it is wise to take multivitamin tablets while experiencing canker sores. Sometimes pain relievers are used to treat pain of canker sores. Tropical pain relievers like benzocaine are used to treat canker sores. There are a lot of over the counter medicines which can be used to treat canker sores. Rinsing with warm water, avoiding acidic foods etc. also helps to relieve pain. In some cases, doctors prescribe some strong pain killers too, according to the depth of pain felt. Corticosteroid rinsing and similar medications also provide relief.

There are some other causes for oral ulcers like canker sores. Viral infections like herpes infections also cause clusters of small blisters. They are also called cold sores or fever blisters. They are usually seen in the upper lip or such mucus membranous parts. Mostly cold sores are not seen in tongue. But there are viral infections which cause tongue sores. But they are not seen to be recurring. There are some intestinal diseases which cause inflammation in tongue. Crohn’s disease is another disorder which causes intestinal inflammation and tongue sores. They are also associated with back pain, cramps and diarrhea. If you have these symptoms also, it is better to think this way.

Auto-immune diseases are also seen to cause tongue inflammation and sores. They are rarely seen to cause diseases which can suppress body immune system. They include behcet’sdisease which cause genital ulcers, eye inflammation and eye pain and reduced vision. Sometimes joint pains are also associated with this. Another disease associated with this is the Systemic lupus. This is marked with skin rash, joint pain and inflammation in other parts of body. It includes inflammation in heart, lungs, kidneys and such internal organs. Reiter’s disease is another infection seen associated with sexually transmitted diseases and chronic diarrhea. It also triggers the immune system of body itself to attack various parts of body, causing wide inflammation. It also cause arthritis, pain while urinating and other similar features. Allergic reactions of certain foods also can cause tongue inflammation. If it happens when you take certain foods, it is better to consult your doctor immediately. Some foods can be poisonous to certain people who are allergic to that foods. So it ie better avoid such foods. Hope my answer was helpful. Take care.