Hello, u had guessed it right, it could be oral thrush
.. which might be due to overdosage of the antibiotics or decreased immunity, or it can be part of any other white lesion of oral mucosa
.. which includes nicotinic stomatiis, allergic stomatitis
clinical examination and brush/exfoliative biopsy will confirm the lesion.. consult an oral medicine and diagnosis specialist for same..
meanwhile keep your tongue clean daily.. do warm saline gargles.. maintain oral hygiene