Hi,
Well, brown spots on tongue that are spreading can be due to causes like, it can be a normal
melanin pigmentation that can occur on tongue surface, over the tongue papillae and also on mucosal surfaces like cheek and roof of mouth. Other cause can be
black hairy tongue that can be due to bacterial or fungal overgrowth, intake of certain bismuth containing medications, chronic intake of soft foods, poor
oral hygiene etc.
These reasons are common to occur and are not anything to be worried for. But in case if the patches are raised then they have to be taken care of and a
biopsy might be needed for confirmation. As of now you can consult an Oral Physician and get a clinical evaluation done and treatment will be done accordingly.
However start gargling with 1:1 solution of
hydrogen peroxide and water. You can use a tongue scraper to clean your tongue. Chew hard foods like apples, carrots etc.
Hope this information helps. Let me know if I can assist you further.
Regards,
Dr. Honey Arora