Hi..
Welcome to HEALTHCARE MAGIC..
I have gone through your query and can understand..
As per your complain cottage cheese like coating over the back of tongue seems to be due to yeast infection known as
Oral Thrush and cheesy white coating is a classical feature of thrush..
Soreness of tongue is also due to infection only..
Sour taste can be due to
acid reflux or at times can be due to infection also..
Small round swirls can be due to formation of Apthous Ulcers..
I would suggest you to consult an Oral Physician and get evaluated and a thorough clinical evaluation can help in diagnosis and treatment can be planned accordingly..
If thrush is confirmed as the cause you can be advised to take anti-fungal medications like
nystatin mouthwash and sucking
clotrimazole lozenges..
Take ample of probiotics like Yoghurt and garlic..
Gargle with a numbing mouthwash if there is soreness of tongue and suck ice pops..
Hope this information helps..
Thanks and regards.
Dr.Honey Nandwani Arora.