A vitamin B(s) deficiency or Riboflavin deficiency (vitamin B2), anemia, Iron deficiency anemia
, Pernicious anemia
, minor viral disease, smoking, etc., etc., etc.
There are 26 medical conditions causing White tongue. Oral candidiasis, Candidiasis, Leukoplakia, Dehydration, Immunosuppression, etc., etc., etc.
You said that doctor put you on antibiotics, perhaps you need to be on the medication a little longer. Oral thrush is very hard to clear up and takes the longest to clear.