Mouth ulcers won't heal. It be cured.

I have been having mouth ulcers on right cheek that wont heal. Its pain less and doest look much scary. I am having this issue since almost more than three years, i used to chew pan masala and did for almost year but eversince i had this issue i left chewing pan masala. Intially it started with white patch with rough dry skin that didn't let me open my mouth properly.but later on that cured. Now it became mild red patch with tooth cut mark that wouldn't heal. I was regular smoker and left since last 6-7 months. Now smoke/drink occasionally. I have visited few doctors including dentists but no one recomeneded biopsy. Every one advised to eat vitamins tablets and normal mouth gels on ulcer. I am now worried as it wouldn't heal and some times i feel mild pain and swelling.please i need someone who can actually tell me what is in my mouth and how will it be cured.