Coating back of tongue

does anyone know what this is? had this for around 3/4 months now, coating more towards the back of tongue, it doesnt really come off after i scrape it, ive tried salt walter, fluoride mouth wash, i brush my tongue and floss every night. i had a tongue swab at the hospital which came back clear.. just wondering if anyone has the same or knows what it could be please?

Hi there- looks really similar to what I have. Went to the pharmacist a couple of days ago and she said it was thrush. She gave me a weeks worth of anti-fungal gel which clears the white stuff immediately but then it comes back about 30 mins afterwards so you have to keep using it. Do you find that you feel like you’ve constantly got to clear your throat?

what causes it?