Hi..
Welcome to HEALTHCARE MAGIC..
I have gone through your query and can understand your concerns..
As per your complain it seems that you are suffering from STOMATITIS which is inflammation of mucous membranes of mouth  and tongue is most common to get affected due to which there redness and pain in mouth and there is raw feeling..
It can occur due to a number of conditions like 
Nutritional deficiency of 
Vitamin B12, Iron and 
folic acid, dry mouth, yeast infection like thrush, 
allergic reaction to certain medication like Antibiotics, anti convulsants, 
anti cancer drugs etc.
Chewing tobacco, smoking etc can also lead to stomatitis..
Viral infection in mouth can also lead to stomatitis and is known as HERPATIC STOMATITIS.
You should consult an Oral Physician and get evaluated to get ruled out for the exact cause of stomatitis and get treated accordingly..
As of now you can do cold water rinses and suck on ice pops for relief..
Drink plenty of water and 2 litres is still less as you should drink 3 to 4 litres a day.
Avoid hot and spicy food..
Take a cold bland diet..
Hope this information helps..
Thanks and regards..
Dr.Honey Nandwani Arora..