My tongue has a slightly metallic, prickly, tingly taste most of the time. I particularly notice it when I am eating, especially fizzy and spicy foods?

Allergy. The most common cause of this symptom is cinnamon stomatitis or allergy to cinnamon containing compounds. However, things like "geographic" tongue can also have similar findings. Nutritional deficiencies can give similar findings.
Possible allergy. This could be an allergy, especially to spicy foods or certain vitamin deficiencies/systemic conditions manifest on the tongue. Probably wise to see the family M.D. For routing blood tests and your dentist to evaluate for abnormalities of your tongue.