Hello,
Highly unlinkely that your schizophrenic medication can cause any white patches on the tongue. Secondly, if it is from the tooth it would result in a traumatic ulcer which is usually reddish in colour.
A clinical picture of the lesion would help in better diagnosis. The white patch on tongue could be an isolated presentation, which could be geographic tongue, leukoplakia, candidiasis etc.. again a clinical examination is needed.
Next Steps
Consult a dentist regarding your carious tooth and a Maxillofacial surgeon in view of the white patch