I have painful mouth sores on my tongue and inside cheeks. sometimes have a small white/yellow bubble and are always red. low iron and b12.

See a dentist: If you want to know what is the cause of your sores and what treatment is available to you, you will have to see a dentist. We can't diagnose and treat you over the internet.

Probably not main ca: The probable cause is probably viral. They could be caused by stress and therefore b 12 may help. See your dentist if there over 5 days. They may resolve on there own and stay away from acidic juices and foods.