Tongue itch. Itching is a frequent symptom of allergies. Sometimes fresh fruits or vegetables can trigger an allergic reaction that includes itchy tongue, roof of mouth and throat. This is a cross reactive protein between pollens and the fresh food. An allergist can help you try to identify the trigger of the itching through skin or blood tests. Finding the cause is preferred over covering up the symptoms.
Oral Hygiene. I'm wondering what types of toothpastes and rinses are you using. Hopefully, not peroxide or bleach. I have had patients reporting this and found that they were rinsing with bleach and water? Maybe adjust your hygiene product to see if that helps.