It seems possible that you have developed an inflammation of the tongue - the condition is called glossitis. Glossitis may be due to viral or bacterial infection. If there is superimposed fungal infection, it can feel like there is a coating on the tongue.
Please consult a doctor - if the inflammation is severe you may need an antibiotic. You will also need blood tests to check for anemia or vit B deficiency.
Meanwhile, please rinse your mouth with a chlorhexidene mouth wash available without prescription at any pharmacy. Also take Ibuprofen, 200mg thrice daily for 3 days. Continue to drink plenty or water to flush out your mouth.
I hope this helps.
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