Hello and thank you for your question.
For a sore tongue that has been sore for three years but does not have any physical markings I would suggest that the tongue may not be the source of the pain. You may be experiencing what is called
referred pain. In other words you feel the pain in your tongue but it may be originating in another part of your body, like an ulcer in your stomach, or a tumor in your jaw (these are just examples not me stating you have these). Your tongue pain may be caused by
glossitis, inflammation in the tongue as well. Causes of this include
vitamin B12 deficiency, Sjogren's syndrome, and side effects of medications or
chemotherapy.
Since you are chronically taking
prilosec, this may be due to a vitamin B12 deficiency. According to one study I read when used over a long period of time, such as three years or more, prilosec can cause a vitamin B-12 deficiency. Signs of a B-12 deficiency include a sore tongue, unusual and unexplained weakness and
numbness and
tingling in the hands and feet.
I hope this helps you in your discovery of your problem. I recommend taking a Multi-B vitamin and see if the issue subsides in a few weeks.
Best wishes and good health
Dr. Ward