Throat problems

I am an 18 year old male who weighs about 60kg does not smoke and is on no medications.

Three days ago I noticed a terrible taste that was coming from the back of my throat that I can only describe as similar to the smell of an old dirty fish tank, today I had a look back there since it didn't go away thinking it was tonsil stones but instead there is a number of pustules (7 or 8) at the back of my throat and on the back of my tounge but there is no pain at all. What might be the cause of this?