Your symptoms seem to look a lot like Oral Submucous Fibrosis ie OSMF. The white rubbery bands are caused by betel nut and tobacco use. Can also be caused by other environmental factors and viruses. This is a dangerous situation if not treated early. It will turn malignant soon. Please see a doctor. Do not self medicate and look for temporary solution.

Hi..you need to visit dentist soon. It could be because of oral submucous fibrosis or due to wisdom tooth wrong position. Regards

First of all you have multiple problems which need to be addressed as soon as possible. You should immediately plan for a visit to the dentist for a proper clinical examination. The right treatment will be based on evaluation of the current condition. And most importantly there is no particular vitamin or food which can prevent oral cancer. It is the absence of habits like tobacco and alcohol and a generally healthy diet and Lifestyle which contribute to oral Cancer prevention. Despite all that there are many other factors (for example some viruses) which can still cause oral cancer in patients who are otherwise normal.