thanks for your query.
Positive ANA test is sensitive test for autoimmune diseases however it may be false positive. It may be positive in Systemic lupus erythematosus
,Sjögren's syndrome, inflammatory bowel disease
or in some medications. As you are also having peeling oral mucosa
, you are highly recommended to visit immunologist, he may advise biopsy and immunofluorescence study to reach any diagnosis.
Hope it helps