White spots on the tongue with some redness upper left gum is it possible to have symptoms of oral cancer after quiting smoking after 1 year or can antibiotics cause this just finished bactrim (sulfamethoxazole and trimethoprim) ?

See a dentist: It's very difficult to say what it could be without seeing the patient, it could possibly be nothing or candida (Thrush)? See a dentist for evaluation and treatment if needed. Good luck.

Sounds like thrush: Yes oral cancer can occur after quitting tobacco. But congratulations on quitting. It's always one of the very best things anyone can do for their health. Oral cancer would be expected to have a single lesion, not multiple spots. Your description sounds like thrush, which is common after antibiotics. But the only way to know is to have an oral exam by your medical doctor or dentist. Good luck.